I have two carts. One is the cab dolly and I made a platform with wheels, then put a pedestal on top of that to emulate the cab mounting. I can set it on the floor for most work, but also on the firewall and even tilted to a firewall/roof combo so I can get to the underside areas better.
The other cart is in my bolt bucket and is configurable to put a bed on, fenders, hoods, panels, you name it depending on the attachments. I even put the front and rear ends on it to work on them.
I also made a frame rotisserie that has raise/lower, rotates 360 degrees and rolls nicely. Made the bulk of that out of modified engine stands.
Other than those things, tables that put things at a comfortable working height are nice to have.
