I would add for the "doubting thomas" that unless you have a need for a higher gearset, or the rear end is coming from a known, unmolested truck, take the rear cover off, count the teeth on the ring and pinion, just to make sure. I know I bought mine w/o opening it up, and got lucky. My advice if I were ever buying another one, I'd take the 5 minutes to pop the cover off and count the gears.
