New owner with a few questions.

I just recently bought a 1994 king cab 4x4, I want to know if it was a good buy, I got for $300 Cdn. I also wanna know which rear diff it has but can't find the sticker in the door jam. I'm not sure the trim level cause the emblems are gone but it is very basic, no power windows or locks, no a/c, no cruise, nothing. it does have the 3.0L v6 and a 5 speed, it also has manual locking hubs which I hear are better. Is there another way to find out which rear diff it has? Is there a posi rear diff for these trucks? maybe from another truck make?
thanks for any help.

Jeff.