Look for a Ford Maverick. They come with the narrowest 8" rear end that Ford made, about 56.5 inches from flange to flange. Generally these are open differentials with 2.79 or 3.0 gears. Another option this a Ford Explorer. I think they are 58.5 or 59 inchers. Neat thing about them is after 95 they have disk brakes. Also many of them have Traction-Lok and either 3.55 or 3.73 gear ratio. Another one I have seen folks using is the S-10, but I don't have dimensions or specifics on those.

I think any of these should hold up in a light vehicle with up to 350-400 hp.

Pat