I see some have welded these on while the car is on a rotisserie. Has anyone had issues and if the car is currently on a rotisserie how can I make sure the doors will shut? I can't take it off but with the whole bottom clean I would like to install these.
I installed mine on the rotisserie and reinforced the door opening, my rotisserie came with bolt in door bar reinforcements but you could tack weld some 1" square tubing also. Everything fit like a glove during assembly.
There are dozens of people on this site and others that have installed these, and other, frame connectors with the car on a rotisserie. I have yet to see anyone that's done it that way say they had issues with body fits, alignments, etc. With appropriate precautions (door bars, etc) it shouldn't be an issue. Same goes for the car not sitting on it's suspension for installation. If you don't have the means to weld the connectors in with the car on it's wheels, level the car and support it near the suspension points. Check to make sure your door gaps and body fits are what you want, then weld away.
I would always recommend using some kind of door reinforcement while the car is on a rotisserie anyway, just like I would always recommend making sure your door gaps/body fits are right before installing any chassis reinforcements. But honestly, I've never seen a thread or talked to anyone that messed up their body fits or alignments by adding frame connectors, regardless of the method of installation. I'm sure it can be done, but I think it's probably harder to do than most folks seem to think.