Troubleshoot please help!!!

I have a 1992 GMC Jimmy V6 4.3L vortec 4x4. It ran beautiful all the way up till this past saturday. Now it is making a horrible clicking noise while accelerating in overdrive,drive,2nd,and 1st it does NOT click while in nuetral, park, or reverse(even while accelerating). the clicking scales with my speed. My buddy was the one it first happened to and he told me that once he got to 45mph it stopped until he reached 70mph. i have done my best to figure it out but am at a loss. my poor baby sounds like a pissed off lawn mower and it is not cool.

Have you checked the u joints and axel joints?

What area is the clicking comong from?

The clicking as best as i can tell is coming from the front end. I had a buddy check on it for me and he says my 4wd keeps jamming so that it is always active. He tried to jam it into 2wd and got it there for 2secs of unclicking driving. Then he left me with the words of take your wheels off and find some plastic gears and see if you cant unjam them which i can not find.

The clicking as best as i can tell is coming from the front end. I had a buddy check on it for me and he says my 4wd keeps jamming so that it is always active. He tried to jam it into 2wd and got it there for 2secs of unclicking driving. Then he left me with the words of take your wheels off and find some plastic gears and see if you cant unjam them which i can not find.

I would check and see if front axel is locking in and out good.
Good luck