Kingpimp

iTrader: (1)

I have a 99 z-71. When I **** to reverse from a stop, I get a loud clunk. I had someone shift from D to R while I went under the truck and listened. The clunk seems to be coming from the T-case, but what got my attention was that the front drive shaft was spinning even though the selector says 2wd. I did a burnout, drifted on some wet roads and concluded that the front wheels were not spinning under power from the T-case. 4wd worked fine after I pressed the button and shifted into 4wd. Is my front driveshaft supposed to spin, even in 2wd?
Another issue is that the whole rear end spins in the same direction a tire would when I push the truck back and forth while the tranny is in park. I removed the lift blocks from the rear, but I torqued and retourqued the bolts. It is difficult to explain this fully, but its like the only thing keeping the rear end from spinning is the yoke from the driveshaft. Here are my questions:

1. Is the front driveshaft supposed to turn while in 2wd??
2. Is the rearend "spin" something I should be concerned about?

Thank you for your time.

cbrich

The front driveshafts always turns, no matter whether its in 2wd or 4wd, this how GM designed the t-case since the 2wd and 4wd selector is located in the front axle and the 4Hi and 4Lo is located in the t-case.

Did you replaced the U-bolts with some shorter ones, when you pulled the blocks out (assuming 3 inch blocks). If yes then you might need to check your spring perches for crackes and to make sure they are welded to your axle. If no, the nuts on the U-bolts tighten against the end of the threads on the U-bolt not the spring plate, to solve this problem you need to tap the u-bolts more or replace them.

As for your clunking sound check the u-joints on the front and rear driveshafts, a good starting point.