Well unfortunately '80 thru '82 Dana 44 "aluminum" rearend gear selection seems slim compared to '63-'79 "cast iron" rearends.
Factory gear sets available were 2.72, 2.87,3.07.
I've only seen 3.55 & 3.70 gear sets offered in the aftermarket for '80-82.
I had 2.72's in mine originally, and then later swapped in a '80 diff with 3.07's. I was a small improvement. I just recently put in a Keisler 5 speed kit. Now even with the 3.07's it launches like it has a 3.90 rearend gear. The overdrive gear help the car to acheive 22 mpg at speeds around 75mph on the highway.
So if the only other available choice up from a 3.07 is 3.55, then you'll probably have better off line performance with dismal fuel economy. So if you want the best of both worlds... I say overdrive transmission. Auto or Manual.
______________
GEN III 5.7L "LS6" Engine swap
TKO500 5 spd.
3.54 Dana 44