I put mine on jackstands, and did my best to level them, (garage floor sucks) the door gaps were all good and didn`t change ! cut mine into the floor and used 2x2 square tubing installed inside the frame on the rear, and welded the full length of the floor, seems to be very stout! they stuck thru the floor about 3/4", put 3/4" ins. in to make it all level before the new carpet, looks pretty decent.
