92' Ranger XLT with 2.9 V6.
I have the textbook clunk or thump when starting from a dead stop. It's getting worse and sometimes I get a second thump after the initial thump while accelerating.
I spent time looking at everything under the truck and I didn't see anything. I'm pretty sure the problem is in the area of drive shaft slip yoke/transfer case.
I have the 2-piece driveshaft.

The first I'll check is the slip yoke. I've done some reading. But I have a couple questions.

1. Do the slip yoke and driveshaft splines need lubricating on my make and model?
2. If I disconnect the driveshaft companion flange at the differential, can I then just pull the driveshaft away from the transfer case to expose the splines?
3. If I need a new slip yoke, I'm not able to determine which one I need. Do I just count splines and take measurements to select the one I need ?

 

I've got an 01 4.0 4x4 with this situation. Upon acceleration from stop - thump, then just a second and - thump. It's not violent but I can definitely feel it. I've had it checked out by two shops, both told be "driveline backlash". I want to have it corrected if possible but sounds like it's nothing they wanted to mess with "just drive it".
Sorry i don't have an answer but I'll be watching this thread too see what answers arise...

 

Motor mounts are fine on mine. I'll look at it more next weekend

 

I got my truck back from the transmission shop a few days ago. The 'thumping' or 'clunking' is gone. So it must have been the transmission. Or maybe it was some other easy driveshaft related fix the
shop decided to include. Thanks.

 

I read the spline shaft in the slip yoke needs to be lubed with a specific, Ford grease. I got mine online for $14 where the nearest dealership wanted $45.
EDIT: As I recall, the Ford grease is a "Teflon grease" and is said to work better. I doubt it's life and death either way.
Some members here claim to use regular grease with good results. Others say common greases simply require redoing the job in a few years.

I have the one piece driveshaft but I think there's a slip yoke at its forward end which requires removal of a boot.

 

I can't see going to all the trouble to buy Ford Grease. My Chilton manual says to use an all purpose chassis grease, or something to that effect.