First pic is my dolly I got from harbor freight for like $4 on sale.
Ps: I bet anyone pulling the trans through the floor was dealing with a 3 speed. The 4 speed is much bigger and weighs about 150 pounds I think.
I get those HF moving dollies for the casters on them. Way cheaper than buying the same casters from HF.

I wouldn't try to pull even a 3-speed up thru the floor. The acesss is just too small, and then you'd have to drag the tranny out the door. Dropping it down using an engine hoist is the way to go.