Here it is, I was swapping in a rear driveshaft when I finally found the answer to my mysterious vibration problems. The nut on the pinion shaft was not completely tight. The plate that the driveshaft bolts to was a little wobbely(obviously the answer to my vibes).
I tightened the nut and took it up on the freeway, not to my surprise it is now smooth as silk.
Question-What do I do now?
What should I look for?
What would cause this to happen?
I need to know what to torque that nut to?
Has this ever happened to anyone before?

On one hand I'm happy cause I found my problem.
On the other I'm afraid I will see some rearend problems in the future.LOL

There is no specified torque that it needs to be at. The rearend has a crush sleeve type pinion so it's important not to overtorque it.

The bearings could be damaged, how long has it been vibrating?

I would buy some red locktite, take the nut off, put locktite on the threads, and tighten it back down by hand. As soon as it gets tight, (tighter than it has been to this point), stop, you're up against the crush sleeve. Leave it at that if the pinion doesn't have any play in it. If it has play tighten it a little at a time until the play is gone, then stop. If you overtighten it you put too much preload on the bearings and you'll smoke em.

Good luck.

I really appreciate your help!!

You mean the loose nut behind the wheel has now been tightened down?

Dang!

Hey Leggo, I take it you made it back ok. Jim said there was a h*** of a wreck on 80 by the time he got there. Glad to hear you got your bad vibes fixed. If your axle does go out, you know where one is :)

Later

I hope I dont need your axle!! LOL
After that drive home on sunday I wont be doing any extra driving this week.
Me and Dan were cruising at about 70-75 mph when we hit a patch of black Ice on dry roads,totally unexpected.
After staring at the gaurdrail about 5 feet infront of the truck we managed to pull it back straight. And we almost lost the hood.
About a half hour later the road turned to pure ice for 20 miles..........uuuuugggghhhhh!!
I have lots of video of the 20 mile stretch of pure ice, four tractor trailers and a couple dozen cars in the median and ditch. I got home a little after 11.

Glad you got home safely, but it must have put a crimp in your Monday morning :) Rt 80 in PA is notorious for becoming a junkyard for vehicles in the winter. There are almost always semi's jacknifed and cars in ditches all the time.

I will send you those pictures of your truck as soon as I can.
I am moving this week and am trying to minimize my time on the 'puter.

leggo,

Are you talking about the flange that the rear of the driveshaft mounts to? I'm almost positive there was a TSB regarding the torque of the nut holding it in place. If memory serves the updated torque spec was 250 lbs.

I think Kampy is reffering to the pinion gear adjustment itself (inside the diff), not the flange retaining nut. Correct me if I'm wrong...

yes that is the flange I am speaking of. After tightening it up I have not yet experienced any problems(knock on wood!). I will See About getting atorque wrench that will handle 250pounds.
Do you remember where that tsb was?
Thank you for the info.

I'd double check that TSB, the nut on the pinion retains it as well as setting the pinion bearing preload, overtighten it and it will destroy the bearings in short order.

I'm almost positive I saw that on Dr. Bob's site but please do double check. I will continue looking...

Looks like that TSB was on the front flange. Sorry for the confusion...