U.S. Rents, or if you have them ABA DABA rents. I've always used ABA DABA since they were very close to my house. You can get the break-away ones that come all apart and go in the back of a vehicle (I brought one home in a '68 Cougar many years ago), or one on wheels that you just hook to a ball hitch and towe it home (much easier if you have the ball hitch). As many times as I've rented one, I could have bought one by now, but there's just no place to store it.
Yes, the tire trick in the back of a pickup works even better with the tranny attached. The tire is just to "form" to the shape of the engine and keep it from rolling around. I usually just use blocks of wood to wedge the engine into a good postion and then drive carefully on the way home.
Good luck, HTH.