I have done a lot of research online to try and figure out this issue.

THE PROBLEM: Clunk going from stop to go and vice versa

Fixed the Following:
Greased Slip Yoke.
Rear Shock Absorbers
Rear leaf spring brackets/shackles
Checked the U joints there not bad.

The issue is still there. My question is did something go bad in the rear differential. When I lifted up the truck only one tire was spinning at idle but both spun when given gas. there is a slight Whistling noise in reverse but it doesn't sound like its coming from near the rear axel.

When looking at the slip yoke it looks like it is going in and out(. Is there something that makes the yoke a little more stationary?

Anyone with this kind of expertise I would be very much thankful

Thanks

 

Truck details, please?

 

I had the same problem with my 2005 F150 4x4. when it started the rip you off-ship did the same to mine, grease leaf springs etc. finally they greased the u-joint and it helped for a while. they did it repeatedly until warranty was out. replaced the driveshaft haven't had a problem in 4 years.

 

Slip yokes must be greased with special teflon grease or they will still make noise. My guess is a u-joint is bad or the pinion flange is loose if it is not the slip yoke. Also I am curious to know how you tested the u-joint to determine it is okay? Lots of movement in the slip yoke while turning the wheels indicates a dry u-joint.