Adding on top @BriefYayyayyay answer, I found the official Mesh Ids for the Parts.
Head: rbxasset:///avatar/heads/head.mesh
Left Arm: rbxasset:///avatar/meshes/leftarm.mesh
Right Arm: rbxasset:///avatar/meshes/rightarm.mesh
Left Leg: rbxasset:///avatar/meshes/leftleg.mesh
Right Leg: rbxasset:///avatar/meshes/rightleg.mesh
Torso: rbxasset:///avatar/meshes/torso.mesh