8 3/4 rear
The 8.25 has it's limitations for sure, but I believe it's closer in strength to say, a Chevy 12-bolt, than people think. It's not an 8.8 Ford, or even a 9.25" Chrysler by a longshot, but I have used several, especially one, beyond expectations with success. My '71 Demon started out as a 318/904/7.25" car and I built a budget street/strip car when I was going through a divorce, as a cheap distraction. The car came with a set of fresh 2.02 J-heads with double springs, a Cam Dynamics solid camshaft (and jumbled lifters), and Crane adjustable iron rockers in the trunk, and a 2.45 geared 8.25 loose on the side. I have a friend that works for the Dodge dealer that "appropriated" a Dakota Sure Grip and some 3.92 gears for me, so I went with the 8.25". I built a KB107 .030" '71 block 360 with the J-heads, a windage tray, Torker II intake/750 AFB and a swap-meet new .528" solid Purpleshaft. The car ran instant high 12s on drag radials, and with slicks ran mid 12s after adding Crane 1.6 rockers and a AED 750 carb. I used to hot lap it and it was very consistent at 109mph, I put hundreds of runs in that configuration, killing one 904 converter and inspecting the 999 trans I built for it (was fine) while it was out. Then, about 3yrs later I built a 416 pump gas, dished piston, Edelbrock headed motor with about 525hp and ran the same converter/trans/rear and went 11.20s/30s @119-120mph with the same rear, still street driving it. It would pull the tires as Rob stated, just a little, but the SS springs were tired by this point and it was inconsistent, even with 10.5 slicks, so I ladder-bar/mini-tubbed it with an 8.75/Moser axles/coilovers etc. I still have the rear and just moved the springs over 1" with the old MP offset shackle/hanger kit in a 4dr '71 Valiant I plan to turbo 318 someday, using the whole original Demon suspension setup.