That is a Dana 60 rear. I use to run one in my Blazer.
Ridin' High is correct the Carrier for 4:10/4:11 ratios won't accept a 4:56 or visa versa. Good time to upgrade to a Posi or locker(duno what the truck is being built for?)
D44 caster is not adjustable on a D44 front. The knuckels set your caster. I could be wrong but the 10yrs+ I spent with my D44, torn down many many times, upgrades all the parts seals etc... never heard of a caster adjustment? But again I could be missing something so? There are cone sleaves that the ball joints seat into. When I replaced my ball joints I replaced the cone sleaves too, pulled um out with the special socket and then turned in the new ones. I don't think that is an adjustable sleave, it just seats in tight.
Good Luck and post up some pics of your project!
Burt