A while back I read in here that there were a few people having driveline problems. They had swapped u joints, brgs, etc and the problem still persists. Yes I agree, a sloppy diff. can cause the noises, clunking etc. Here's what I found out a couple weeks ago. My 91 XLT 4x4 4L did pretty much everything people described. I couldn't lug the motor, as the jerking form the engine would launch me against the windshield, then suck me back into my seat. A little exaggerated, but non the less... I manufactured a stainless muffler out of 2 feet of 14 ga 6" tubing, a couple pieces of 3/16" hole, 1/4" center 16 ga screen rolled into tubes (tricky stuff to TIG weld let me tell ya), a 14 ga baffle thet ran the length of the muffler, 2" in and out. A very simple design I worked out after surfing the net for a half hour. I welded the thing on, fired my truck up and it purred. So quiet the only way I could tell it was running was the noise from my power steering pump (I swear you can hear Ford and Merc p/s pumps a block away):P I'm a hunter and I want a quiet truck for sneaking up on helpless little animals I drove my truck out of the shop and didn't hear or feel the clunk or lurching. I thought it was my imagination, but the truck is still as smooth as silk. I can run in all gears at an idle. I took a good look down my aluminized mild steel, rusted, clogged muffler. No woonder my truck wouldn't breath properly. There is a noticable increase in power and fuel economy. All you boyz having trouble with drivelines should take a good look at the exhaust system on your truck. Cheaper thn fixing a torn out rear end.
Rick

 

When you changed the muffler did you change the catalytic converter also. My 93 ranger has the typical ford shift from park to drive.

 

Nope, I left the cat converter in. After weighing the cost of a new one, and the threat of the air care police not passing my truck if I took it out, I decided to leave it in.