diff --git a/linode_api4/groups/image.py b/linode_api4/groups/image.py
index e644dc16..fda56fb0 100644
--- a/linode_api4/groups/image.py
+++ b/linode_api4/groups/image.py
@@ -4,7 +4,8 @@
 
 from linode_api4.errors import UnexpectedResponseError
 from linode_api4.groups import Group
-from linode_api4.objects import Base, Disk, Image
+from linode_api4.objects import Disk, Image
+from linode_api4.objects.base import _flatten_request_body_recursive
 from linode_api4.util import drop_null_keys
 
 
@@ -58,7 +59,7 @@ def create(
         :rtype: Image
         """
         params = {
-            "disk_id": disk.id if issubclass(type(disk), Base) else disk,
+            "disk_id": disk,
             "label": label,
             "description": description,
             "tags": tags,
@@ -67,7 +68,10 @@ def create(
         if cloud_init:
             params["cloud_init"] = cloud_init
 
-        result = self.client.post("/images", data=drop_null_keys(params))
+        result = self.client.post(
+            "/images",
+            data=_flatten_request_body_recursive(drop_null_keys(params)),
+        )
 
         if not "id" in result:
             raise UnexpectedResponseError(
diff --git a/linode_api4/groups/linode.py b/linode_api4/groups/linode.py
index da3ba501..48f0d43b 100644
--- a/linode_api4/groups/linode.py
+++ b/linode_api4/groups/linode.py
@@ -1,25 +1,29 @@
 import base64
 import os
 from collections.abc import Iterable
-from typing import Optional, Union
+from typing import Any, Dict, Optional, Union
 
-from linode_api4 import InstanceDiskEncryptionType
 from linode_api4.common import load_and_validate_keys
 from linode_api4.errors import UnexpectedResponseError
 from linode_api4.groups import Group
 from linode_api4.objects import (
-    Base,
     ConfigInterface,
     Firewall,
-    Image,
     Instance,
+    InstanceDiskEncryptionType,
     Kernel,
+    PlacementGroup,
     StackScript,
     Type,
 )
+from linode_api4.objects.base import _flatten_request_body_recursive
 from linode_api4.objects.filtering import Filter
-from linode_api4.objects.linode import _expand_placement_group_assignment
-from linode_api4.paginated_list import PaginatedList
+from linode_api4.objects.linode import (
+    Backup,
+    InstancePlacementGroupAssignment,
+    _expand_placement_group_assignment,
+)
+from linode_api4.util import drop_null_keys
 
 
 class LinodeGroup(Group):
@@ -135,9 +139,20 @@ def instance_create(
         region,
         image=None,
         authorized_keys=None,
+        firewall: Optional[Union[Firewall, int]] = None,
+        backup: Optional[Union[Backup, int]] = None,
+        stackscript: Optional[Union[StackScript, int]] = None,
         disk_encryption: Optional[
             Union[InstanceDiskEncryptionType, str]
         ] = None,
+        placement_group: Optional[
+            Union[
+                InstancePlacementGroupAssignment,
+                PlacementGroup,
+                Dict[str, Any],
+                int,
+            ]
+        ] = None,
         **kwargs,
     ):
         """
@@ -290,65 +305,45 @@ def instance_create(
                                          This usually indicates that you are using
                                          an outdated library.
         """
+
         ret_pass = None
         if image and not "root_pass" in kwargs:
             ret_pass = Instance.generate_root_password()
             kwargs["root_pass"] = ret_pass
 
-        authorized_keys = load_and_validate_keys(authorized_keys)
-
-        if "stackscript" in kwargs:
-            # translate stackscripts
-            kwargs["stackscript_id"] = (
-                kwargs["stackscript"].id
-                if issubclass(type(kwargs["stackscript"]), Base)
-                else kwargs["stackscript"]
-            )
-            del kwargs["stackscript"]
-
-        if "backup" in kwargs:
-            # translate backups
-            kwargs["backup_id"] = (
-                kwargs["backup"].id
-                if issubclass(type(kwargs["backup"]), Base)
-                else kwargs["backup"]
-            )
-            del kwargs["backup"]
-
-        if "firewall" in kwargs:
-            fw = kwargs.pop("firewall")
-            kwargs["firewall_id"] = fw.id if isinstance(fw, Firewall) else fw
-
-        if "interfaces" in kwargs:
-            interfaces = kwargs.get("interfaces")
-            if interfaces is not None and isinstance(interfaces, Iterable):
-                kwargs["interfaces"] = [
-                    i._serialize() if isinstance(i, ConfigInterface) else i
-                    for i in interfaces
-                ]
-
-        if "placement_group" in kwargs:
-            kwargs["placement_group"] = _expand_placement_group_assignment(
-                kwargs.get("placement_group")
-            )
+        interfaces = kwargs.get("interfaces", None)
+        if interfaces is not None and isinstance(interfaces, Iterable):
+            kwargs["interfaces"] = [
+                i._serialize() if isinstance(i, ConfigInterface) else i
+                for i in interfaces
+            ]
 
         params = {
-            "type": ltype.id if issubclass(type(ltype), Base) else ltype,
-            "region": region.id if issubclass(type(region), Base) else region,
-            "image": (
-                (image.id if issubclass(type(image), Base) else image)
-                if image
+            "type": ltype,
+            "region": region,
+            "image": image,
+            "authorized_keys": load_and_validate_keys(authorized_keys),
+            # These will automatically be flattened below
+            "firewall_id": firewall,
+            "backup_id": backup,
+            "stackscript_id": stackscript,
+            # Special cases
+            "disk_encryption": (
+                str(disk_encryption) if disk_encryption else None
+            ),
+            "placement_group": (
+                _expand_placement_group_assignment(placement_group)
+                if placement_group
                 else None
             ),
-            "authorized_keys": authorized_keys,
         }
 
-        if disk_encryption is not None:
-            params["disk_encryption"] = str(disk_encryption)
-
         params.update(kwargs)
 
-        result = self.client.post("/linode/instances", data=params)
+        result = self.client.post(
+            "/linode/instances",
+            data=_flatten_request_body_recursive(drop_null_keys(params)),
+        )
 
         if not "id" in result:
             raise UnexpectedResponseError(
@@ -421,19 +416,6 @@ def stackscript_create(
         :returns: The new StackScript
         :rtype: StackScript
         """
-        image_list = None
-        if type(images) is list or type(images) is PaginatedList:
-            image_list = [
-                d.id if issubclass(type(d), Base) else d for d in images
-            ]
-        elif type(images) is Image:
-            image_list = [images.id]
-        elif type(images) is str:
-            image_list = [images]
-        else:
-            raise ValueError(
-                "images must be a list of Images or a single Image"
-            )
 
         script_body = script
         if not script.startswith("#!"):
@@ -448,14 +430,17 @@ def stackscript_create(
 
         params = {
             "label": label,
-            "images": image_list,
+            "images": images,
             "is_public": public,
             "script": script_body,
             "description": desc if desc else "",
         }
         params.update(kwargs)
 
-        result = self.client.post("/linode/stackscripts", data=params)
+        result = self.client.post(
+            "/linode/stackscripts",
+            data=_flatten_request_body_recursive(params),
+        )
 
         if not "id" in result:
             raise UnexpectedResponseError(
diff --git a/linode_api4/groups/volume.py b/linode_api4/groups/volume.py
index 6e879c3d..39d0aeaa 100644
--- a/linode_api4/groups/volume.py
+++ b/linode_api4/groups/volume.py
@@ -1,6 +1,7 @@
 from linode_api4.errors import UnexpectedResponseError
 from linode_api4.groups import Group
-from linode_api4.objects import Base, Volume, VolumeType
+from linode_api4.objects import Volume, VolumeType
+from linode_api4.objects.base import _flatten_request_body_recursive
 
 
 class VolumeGroup(Group):
@@ -57,14 +58,15 @@ def create(self, label, region=None, linode=None, size=20, **kwargs):
         params = {
             "label": label,
             "size": size,
-            "region": region.id if issubclass(type(region), Base) else region,
-            "linode_id": (
-                linode.id if issubclass(type(linode), Base) else linode
-            ),
+            "region": region,
+            "linode_id": linode,
         }
         params.update(kwargs)
 
-        result = self.client.post("/volumes", data=params)
+        result = self.client.post(
+            "/volumes",
+            data=_flatten_request_body_recursive(params),
+        )
 
         if not "id" in result:
             raise UnexpectedResponseError(
diff --git a/linode_api4/objects/linode.py b/linode_api4/objects/linode.py
index cb5c9d9a..8fe71bb7 100644
--- a/linode_api4/objects/linode.py
+++ b/linode_api4/objects/linode.py
@@ -8,10 +8,14 @@
 from typing import Any, Dict, List, Optional, Union
 from urllib import parse
 
-from linode_api4 import util
 from linode_api4.common import load_and_validate_keys
 from linode_api4.errors import UnexpectedResponseError
-from linode_api4.objects.base import Base, MappedObject, Property
+from linode_api4.objects.base import (
+    Base,
+    MappedObject,
+    Property,
+    _flatten_request_body_recursive,
+)
 from linode_api4.objects.dbase import DerivedBase
 from linode_api4.objects.filtering import FilterableAttribute
 from linode_api4.objects.image import Image
@@ -26,6 +30,7 @@
 from linode_api4.objects.serializable import JSONObject, StrEnum
 from linode_api4.objects.vpc import VPC, VPCSubnet
 from linode_api4.paginated_list import PaginatedList
+from linode_api4.util import drop_null_keys
 
 PASSWORD_CHARS = string.ascii_letters + string.digits + string.punctuation
 
@@ -96,14 +101,14 @@ def restore_to(self, linode, **kwargs):
         """
 
         d = {
-            "linode_id": (
-                linode.id if issubclass(type(linode), Base) else linode
-            ),
+            "linode_id": linode,
         }
         d.update(kwargs)
 
         self._client.post(
-            "{}/restore".format(Backup.api_endpoint), model=self, data=d
+            "{}/restore".format(Backup.api_endpoint),
+            model=self,
+            data=_flatten_request_body_recursive(d),
         )
         return True
 
@@ -1063,8 +1068,6 @@ def resize(
         :rtype: bool
         """
 
-        new_type = new_type.id if issubclass(type(new_type), Base) else new_type
-
         params = {
             "type": new_type,
             "allow_auto_disk_resize": allow_auto_disk_resize,
@@ -1073,7 +1076,9 @@ def resize(
         params.update(kwargs)
 
         resp = self._client.post(
-            "{}/resize".format(Instance.api_endpoint), model=self, data=params
+            "{}/resize".format(Instance.api_endpoint),
+            model=self,
+            data=_flatten_request_body_recursive(params),
         )
 
         if "error" in resp:
@@ -1189,7 +1194,7 @@ def config_create(
             param_interfaces.append(interface)
 
         params = {
-            "kernel": kernel.id if issubclass(type(kernel), Base) else kernel,
+            "kernel": kernel,
             "label": (
                 label
                 if label
@@ -1201,7 +1206,9 @@ def config_create(
         params.update(kwargs)
 
         result = self._client.post(
-            "{}/configs".format(Instance.api_endpoint), model=self, data=params
+            "{}/configs".format(Instance.api_endpoint),
+            model=self,
+            data=_flatten_request_body_recursive(params),
         )
         self.invalidate()
 
@@ -1280,6 +1287,7 @@ def disk_create(
             "filesystem": filesystem,
             "authorized_keys": authorized_keys,
             "authorized_users": authorized_users,
+            "stackscript_id": stackscript,
         }
 
         if disk_encryption is not None:
@@ -1288,20 +1296,18 @@ def disk_create(
         if image:
             params.update(
                 {
-                    "image": (
-                        image.id if issubclass(type(image), Base) else image
-                    ),
+                    "image": image,
                     "root_pass": root_pass,
                 }
             )
 
-        if stackscript:
-            params["stackscript_id"] = stackscript.id
-            if stackscript_args:
-                params["stackscript_data"] = stackscript_args
+        if stackscript_args:
+            params["stackscript_data"] = stackscript_args
 
         result = self._client.post(
-            "{}/disks".format(Instance.api_endpoint), model=self, data=params
+            "{}/disks".format(Instance.api_endpoint),
+            model=self,
+            data=_flatten_request_body_recursive(drop_null_keys(params)),
         )
         self.invalidate()
 
@@ -1461,18 +1467,20 @@ def rebuild(
         authorized_keys = load_and_validate_keys(authorized_keys)
 
         params = {
-            "image": image.id if issubclass(type(image), Base) else image,
+            "image": image,
             "root_pass": root_pass,
             "authorized_keys": authorized_keys,
+            "disk_encryption": (
+                str(disk_encryption) if disk_encryption else None
+            ),
         }
 
-        if disk_encryption is not None:
-            params["disk_encryption"] = str(disk_encryption)
-
         params.update(kwargs)
 
         result = self._client.post(
-            "{}/rebuild".format(Instance.api_endpoint), model=self, data=params
+            "{}/rebuild".format(Instance.api_endpoint),
+            model=self,
+            data=_flatten_request_body_recursive(drop_null_keys(params)),
         )
 
         if not "id" in result:
@@ -1597,7 +1605,7 @@ def initiate_migration(
         """
 
         params = {
-            "region": region.id if issubclass(type(region), Base) else region,
+            "region": region,
             "upgrade": upgrade,
             "type": migration_type,
             "placement_group": _expand_placement_group_assignment(
@@ -1605,10 +1613,10 @@ def initiate_migration(
             ),
         }
 
-        util.drop_null_keys(params)
-
         self._client.post(
-            "{}/migrate".format(Instance.api_endpoint), model=self, data=params
+            "{}/migrate".format(Instance.api_endpoint),
+            model=self,
+            data=_flatten_request_body_recursive(drop_null_keys(params)),
         )
 
     def firewalls(self):
@@ -1740,21 +1748,12 @@ def clone(
         if not isinstance(disks, list) and not isinstance(disks, PaginatedList):
             disks = [disks]
 
-        cids = [c.id if issubclass(type(c), Base) else c for c in configs]
-        dids = [d.id if issubclass(type(d), Base) else d for d in disks]
-
         params = {
-            "linode_id": (
-                to_linode.id if issubclass(type(to_linode), Base) else to_linode
-            ),
-            "region": region.id if issubclass(type(region), Base) else region,
-            "type": (
-                instance_type.id
-                if issubclass(type(instance_type), Base)
-                else instance_type
-            ),
-            "configs": cids if cids else None,
-            "disks": dids if dids else None,
+            "linode_id": to_linode,
+            "region": region,
+            "type": instance_type,
+            "configs": configs,
+            "disks": disks,
             "label": label,
             "group": group,
             "with_backups": with_backups,
@@ -1763,10 +1762,10 @@ def clone(
             ),
         }
 
-        util.drop_null_keys(params)
-
         result = self._client.post(
-            "{}/clone".format(Instance.api_endpoint), model=self, data=params
+            "{}/clone".format(Instance.api_endpoint),
+            model=self,
+            data=_flatten_request_body_recursive(drop_null_keys(params)),
         )
 
         if not "id" in result:
diff --git a/linode_api4/objects/volume.py b/linode_api4/objects/volume.py
index 6d49f72c..cda9932a 100644
--- a/linode_api4/objects/volume.py
+++ b/linode_api4/objects/volume.py
@@ -1,8 +1,13 @@
 from linode_api4.common import Price, RegionPrice
 from linode_api4.errors import UnexpectedResponseError
-from linode_api4.objects.base import Base, Property
+from linode_api4.objects.base import (
+    Base,
+    Property,
+    _flatten_request_body_recursive,
+)
 from linode_api4.objects.linode import Instance, Region
 from linode_api4.objects.region import Region
+from linode_api4.util import drop_null_keys
 
 
 class VolumeType(Base):
@@ -63,21 +68,16 @@ def attach(self, to_linode, config=None):
                        If not given, the last booted Config will be chosen.
         :type config: Union[Config, int]
         """
+
+        body = {
+            "linode_id": to_linode,
+            "config": config,
+        }
+
         result = self._client.post(
             "{}/attach".format(Volume.api_endpoint),
             model=self,
-            data={
-                "linode_id": (
-                    to_linode.id
-                    if issubclass(type(to_linode), Base)
-                    else to_linode
-                ),
-                "config": (
-                    None
-                    if not config
-                    else config.id if issubclass(type(config), Base) else config
-                ),
-            },
+            data=_flatten_request_body_recursive(drop_null_keys(body)),
         )
 
         if not "id" in result: