I haven't personally done this swap, but as far as I know it should be a straight swap. May need a conversion u joint, may need to swap your brakes onto the new axle, but as long as you have a 3.73 geared truck, you are good to go. The zr2 axle has a bigger ring and pinion, I believe bigger axle shafts, and are a little bit wider. It's a pretty good upgrade if you are keeping the ifs front.
There's a good thread somewhere on the subject. Also somewhere is a list of the rpo codes in the glove box. I'd double check the gear ratio at the axle instead of going off the glove box.