1991 F-150 5.0L, Auto, 4x4, lift etc

I noticed a sound comming from underneath the truck. I can also feel it in the floorboard.

When I accelerate, I hear a Clunk, Clunk, Clunk, Clunk, Clunk for about 3 sec.

I thought it was a u-joint, so to eliminate a little bit, I took the front driveshaft out. Still did it. Theres no noticable play on the front axle joints,
or on the rear driveshaft near the differential. However there is very little play at the u-joint at the back of the transfer case, however its in the yoke. Theres no other issues other than the noise.

Is this my problem or could it be something else? Tranny? On these truck the transfer case just "floats" correct?

Thanks guys, sorry for the long post.

 

Sounds like the U-joints. Try your shaft removal process with the rear drive shaft and see what happens?

 

that was going to be my next attempt

 

bump

 

Well did you drop the rear drive shaft.

Sometimes everything can feel fine with the shaft mounted, but once it is off, you will be able to find a bad U-joint.

I dropped mine, and though everything felt tight before dropping it. When I articulated the joints on a table, I found that one joint had a "catch" in it and the other felt like it was grinding.

Upon replacing them, I discovered that in the 'grinding' one the needle bearings had turned to dust.

It just goes to show you that things aren't always they first appear to be.

Doug