Manifolds fit my 1981 Z28 perfectly. They cleaned my automatic transmission and installed the floor panel correctly. They fit close to the steering column (1/8 inch). Also, they touched the A-frame on the passenger side, but I sanded the A-frame down and after 10 minutes everything was fine. Finally they are within 1/8 inch of the AC box but all is fine. Engine mounts and body bushings are brand new. I'm not sure if this affected the installation on my computer, but I highly recommend these headers.