It happens when I am accelerating. goes away when I let off the gas. The more I give it, the louder it gets. Sometimes it doesnt do it and sometimes it does. Any ideas? Thanks in advance

 

Check u-joints first....... if that is ok, pull the cover, and have a look. Does your truck have the trac-lok rear diff??

 

Not sure how to tell what rear end I have, or how to tell if the u joints are bad. Sorry guys I am a novice at this.

 

park truck on level ground.
block wheels in both directions.
parking brake off.
transmission in neutral, engine off.
-- make sure its no going to roll --

-- all tension is off the drive line --

inspect u-joints closely.
check that the grease seals are present, and not cracked.
grab the 2 sides of the joint and try to twist them.
any wiggle movement at all in the joint means its bad.
if it passes the wiggle test, stick a long heavy screwdriver through the yoke and pry on it. again, you want no movement.

you either have an "open" diff or a "limited slip" (LSD).
you can look for the old sticker on the axle tube, or the sticker in the glove box or under the hood. the LSD's have clutches which can wear out.

 

Thanks again, I will check for play in the u joints. I cant imagine why the rear end wouldnt be a limited slip, but again I am not sure. I will post back as I know this post could help more than myself.

 

LSD rear was optional on most trucks. (standard on the Off-Road Edition.) Not as common as I would have liked. (my truck doesn't have one.....)

 

After riding in the back of the truck, it seems the clicking is coming from the middle of the truck, and not the rear end. Ill have to wait to figure it out until I replace the fuel pump that went out today Thinking maybe the u joints on the front of the drive shaft?

 

Possibly, do you have a center support bearing on your driveshaft? (two-piece rear driveshaft...)