Whats the best rearend?
 

I'm going to be looking at around 400 horsepower, whats the best rearend for the price, mind you i have a stock 4 cyl 7.5 right now.

explorer 8.8 with 3.73s

Just bolt in a 5L Mustang 8.8" rear and you'll be fine! ...if your hitting the drap strip, might want 31 spline carrier & axles!

^^^+1.... The 8.8 should hold up good with 31 splines. If you want even more ruggedness you could put some C-Clip Eliminators on the old girl so if **** does break, it won't leave you looking like a goofball at the line (plus its safer when an axle does break).