Depending on the hubs you have, you may be able to just remove the cv axles and done (personally, I would also pull the front diff and driveshaft, just to make it easier to work on the front end). Early GMT800 4wd hubs needed the cv's installed to hold them together, later ones and replacements were redesigned so they didn't. At least, this is for the 2500/3500's, the 1500's might be different.
As a data point, my 3500, when I got it 7 years ago, it was a 2wd truck, but the front hubs had splines for cv axles, so when I upgraded the truck to 4wd, I could just slide the cv axles into the hubs.
As a data point, my 3500, when I got it 7 years ago, it was a 2wd truck, but the front hubs had splines for cv axles, so when I upgraded the truck to 4wd, I could just slide the cv axles into the hubs.