The clunk I have is what everyone describes and lubing up my slip yoke seems to cure my clunk for about 8 months. Before I narrowed it down to the slip yoke the ford dealer told me it was weak leaf spring and it was causing a lot of axle wrap which is why my drive line was clunking during acceleration from a stop. So, I had a extra leaf installed and it made it not clunk as much or as hard so it must of minimized the amount of axle wrap that was occuring. I took the truck to a drive line shop and he lubed the slip yoke with lithium grease and sent me on my way with no clunk for about 8 months. I just had it lubed again a couple of months ago and this time he told me they could replace the slip yoke with a redesigned one from ford (Yeah like it's any different now) and they recommended replacing the transfer case seal on the end to keep the grease from oozing out faster. Sounds like people are still having problems with new ones so I'll just keep getting it lubed every so often. Door cracks and clunks = never buying a POS ford again. Going for the new dodge ram in a couple years. I'll let those poor saps guinea pig the their trucks until they get the bugs worked out, if there are any. Should of learned my lesson the first time about buying a first year vehicle after a major body/engine change. It's screwed me once before.

 

Was the engineering rep able to isolate the "thunk" problem?

Thanks for the help.

 

I'd be very interested in knowing that too?