How to tween in a A-Chassis Body?

Hello, I am trying to create “Locker Doors” on a Fire Engine but they open into the middle instead of at the top,

They work in workspace but not in the body of A-Chassis

My Script is:

local TweenService = game:GetService("TweenService")
local part = script.Parent.lockerClosed
	
local DeltaSize = 6.8
local speed = 1.8
local tweenInfo = TweenInfo.new(speed, Enum.EasingStyle.Linear, Enum.EasingDirection.InOut)

on = false
	
script.Parent.lockerClosed.cd.MouseClick:Connect(function()
	if on == false then
		
		local props = {
			Size = part.Size - Vector3.FromAxis(Enum.Axis.Y)*DeltaSize,
			Position = part.Position + Vector3.FromNormalId(Enum.NormalId.Top)*DeltaSize/2	
		}

		local tween = TweenService:Create(part,tweenInfo,props)
		
		tween:Play()
		script.Parent.open:Play()
		script.Parent.lockerClosed.cd.MaxActivationDistance = 0
		wait(1.65)
		
		script.Parent.lockerClosed.Transparency = 1
		script.Parent.lockerOpen.Transparency = 0
		script.Parent.lockerOpen.cd.MaxActivationDistance = 10
		on = true
	end
end)

	

might be because body in a-chassis is welded, you need to put it outside of body for it to work

but then it unanchors and falls off