Help with a 1997 K1500 14 SF question

[evolocomotive]

My son's truck is a 97 K1500 Z71 with F44 RPO code. He has a 9.5 14 bolt SF rear axle that needs a complete rebuild. I want to start getting the parts for it, but I have seen in several places that in 97, GM made some kind of change and to verify which rear end is in it before ordering parts . Can someone please tell me what it is and what I need to look for?

Thanks in advance.