front diff

I have a 99 tahoe 4wd. Trying to take out front diff and hub assemblys. Will 2wd hubs fit 4wd knuckles or will have to change the knuckles too

I have only had my truck about a week before I noticed this problem. It was in auto 4x4 when I drove it off the gravel car lot. There is a concrete entrance before I get to the road. When I was stopped on the entrance way I heard and felt a small pop/clunk I just thought it was the auto 4x4...