Front driveshaft clunk in 2WD

[qlizard]

I've got a 2000 1500 4WD with 71K and the 350 engine. It has been used in the snow and on salted roads. there is some rust underneath. I must admit that I basically have only changed the oil and filters in it, and checked the transmission fluid.

Problem 1 - A couple of days ago I noticed vibration and noise coming from the front end. I've been driving only in 2WD since spring. There is also a strange shifting sound and a feeling from under the driver side floor board when you stop or begin movement. I jacked up the front end and spun the front tire, and the shaft from the front differential spun, as if the hubs were locked (it is not in "auto"). I haven't spun the tires like this before, so I don't know if normally they spin free, but I assumed they did. I pushed "auto" and there was no difference. I tested whether the transfer case engaged when set in 4WD and sure enough the whole thing locked normally. In 2WD, should the wheel spin free without turning the shaft to the differential? Are the hubs not unlocking?

Problem 2 - Last night I put it in reverse (while pushing the brake) and heard a loud clunk sound. I had someone else do it while i was watching underneath and determined it was from the front drive shaft, which is loose. The rear drive shaft is tight. First of all, if it is in 2WD why is it even trying to engage the front drive shaft, and secondly should the front driveshaft be loose? Since problem 1 indicated to me the hubs were locked now I don't even want to drive it to shop until it rains. I'm thinking its already screwed though. I'm going to check and fill the fluids tonight just in case.
any thoughts?

[rdonohoe1]

I have something similar in my 2000 4WD Suburban. I get the clunk when I put it in reverse, as though my u-joints are bad, but they look fine. A friend said there was a "silent recall" for a shim or spacer relating to this clunk - and I'm just now tying to find out more about it when I ran across your posting. I don't want to get a bunch of expensive & unnecessary repairs done just to get this defective part replaced. Drop me a line if you learn anything helpful & I'll do the same - I'm at [email protected]