A couple of other things to ponder. When I did this on my Nova (9" w/GM flange), the rearend had been shortened 1" per side too much. The LS1 calipers are pretty wide (including the brake line connnection, etc) to the extent that they now interferred with the frame. So I went with S10 brakes - the rotors are 1/2" smaller but I didn't consider that an issue for my application. The calipers are much narrower and an added bonus, the e-brake bracket is integral to the backing plate. May not be what you are looking to do but wanted to pass on my experience. -Bob