[blykins]

Definitely go with a positraction rearend. You'll never get any power to the ground whatsoever with an open diff.

Unless you're racing, it would be hard to make a bad decision on what diff to use. The Ford Trac-Lock would work well along with the Auburn diff, or the Detroit True Trac as Dave pointed out.

As for rear suspensions, I prefer the solid axles. Less chance of wheel hop, axles are stronger than half shafts and CV joints, better selection of parts (especially when you compare an 8.8 or 9" Ford to a Jag or Dana 44 rearend).