Drive Train Service

I have a 2002 EXT 4X4. What do you guys recommend as far as service intervals for the front/rear diffs, transfer case, and transmission. GM says that nothing is needed until 100,000 miles, but I remember doing these services more often than that in my old '94 S-10 Blazer. I'm not having any problems with the drive train, but I want to stay on top of the maintenance. Also, what do you recommend for replacement lubricants for the diffs and trans? I've already been told that the transfer case requires proprietary GM lubricant.

Thanks