On acceleration from a dead stop or upon stopping, there is a thump in the drivetrain.Sounds like the rear is catching-up to the rest of the truck. Had the Ujoints and rear fluid changed. Still does it. Is it the diff.pinion gear I heard ford has so much trouble with?

 

When was the last time you changed the transfer case fluid?

When my driveline starts feeling 'sloppy' I replace the transfer case fluid with two quarts of Amsoil MERCON V trans fluid. It works every time (so far)!

I would verify that your transfer case requires Mercon V before adding it. If it requires a different fluid, I would still suggest Amsoil.

 

Changed transfer case fluid with Mercron/Dextron ,as per Ford,30,000 miles ago. So it is due!! Thought about using Mercron V since it is a synthetic.Will try a change of fluid and the lube of the output shaft on the driveshaft.

 

I had the same problem with a 99 Explorer. The slip yoke on the drive shaft had dried out. I'm not sure if it can be greased without taking it apart. You might be able to grease it with a needle.

 

x2. On my 95 Bronco I had the same problem. There should be a rubber boot in the middle of your driveshaft. Unbolt the driveshaft from the rear differential and let it hang. Remove the rubber boot and slide the yoke out...make sure you mark each end when you pull out the yoke as you want to put it back in exactly the same way so your D/S is balanced. Clean off the old grease and then apply some new high heat grease (i've been told to avoid lithium grease here) and slip it back in. Replace rubber boot and secure with some zip ties and bolt back up to the axle. Problem solved.