1993 Chevy K2500 Clunk

I have a 1993 Chevy K2500 that has a driveline or appears to be a driveline clunk mostly in overdrive at 55 mph or more.

I have replace the u joints (greased) and greased the splines but that does not help.

It is periodic and occurs when I am accelerating on a small incline.

It does not clunk at all in four wheel drive but I don't drive over 55 either.

I have only owned the truck for about 3 months and have put 3,000 miles on it. When I purchased the truck the clunk was not there.

Any ideas or thoughts...

I have a 1993 Chevy K2500 that has a driveline or appears to be a driveline clunk mostly in overdrive at 55 mph or more.

I have replace the u joints (greased) and greased the splines but that does not help.

It is periodic and occurs when I am accelerating on a small incline.

It does not clunk at all in four wheel drive but I don't drive over 55 either.

I have only owned the truck for about 3 months and have put 3,000 miles on it. When I purchased the truck the clunk was not there.

Any ideas or thoughts...
The next stop after the u-joints and splines would be the torque convertor; if you have a tach, i would see if the clunk coincides with a 3-400 rpm jump when the TC turns loose.

Thank you...I will check the tach when the clunk appears...lh