He has a 69 if original most likely to be a closed knuckle dana 44 with 3.73 gears
I have had a couple of 70 trucks with open knuckle dana 44 with drums
I would say you also have the sm420 with rockwell tcase in your truck they have shorter front drive shaft and longer rear shaft then the sm465 with np205 tcase
And yes hub and rotors are two peice on a 4x4 not one peice like c10 trucks
I think it was 81 when they switched front diffs
https://torqueking.com/category/1973...44-front-axle/
You will need the tierod setup for the newer diff
The drag link is also longer on the open knuckle dana 44 compared to the closed knuckle
It will turn a bit more sharper too
If your donor truck still has its 12 bolt rear you might want to snag it as well it will be wider then the 69 diff and be closer to the same width as the front diff