You want the Detroit Locker for "3.70 and below" which means it works with ratios from 3.07 to 3.73. That will allow you to use the thick 4.10 ring gear.
The one you don't want is the 3.92 & up... which means 4.10, 4.56, 4.88 etc.
If that 4.10 R&P gear set with the thick ring gear is used, I wouldn't use it since used gears are much (!) harder to get set up properly. I'd go with new standard R&P gears & just get the 3.92 & up Detroit Locker.
What size tires & which transmission do you have?