Why not look into the for 9" rear from an Explorer easy to find gears, rear disc and pretty common to find , 4 1/5 bolt pattern and the right width. Planning on putting one in may 72 Scamp, just easier to build (parts and price) 8 1/4 are good for street strip 300hp will hold up if build right, but have the c-clip issue (not an issue till they brake..). I have a buddy who races chevs 9sec car and runs the Ford rears because they hold up great, easy to find parts are alot of gear options and a heck of alot cheaper and easier to find then a 8 3/4. You could sell your 8 1/4, and use that money to pickup a Ford 9" for...