4wd rear to 2wd

[sb400]

I may have access to an extremely low mileage 3:08 posi rear from an 85ish 4wd truck to replace the open 2:73 in my '84 SWB 2wd. Since I can't actually look at the 4wd rear right now hoping someone could tell me if it would be a bolt in? Can you swap the 5-lug axle shafts and brakes on to the 4wd rear? Are the spring perches in the same place? What about the shock mounts and pinion angles?

Another question - How about swapping an 85 4wd rear to a '72 4wd Blazer? The Blazer already has 6 lug wheels but alas no posi.

Edit: the "new" rear is a 10-bolt from a military truck.