The mechanic moved one of the tires to the front, he said it was worn unevenly-that was the drive wheel and its also out of round.

He checked everything top to bottom, I doubt he pulled the axles. But he did tell me the u joints didnt feel bad, they did have some stiffness, but not bad-so he said he "tweaked them".

My truck now doesnt vibrate as bad at speed and on take off the trasfercase shifter doesnt wiggle back and forth nearly as much as it did-but I can still feel it.

Thats why I am thinking:
A: I know my tires are out of round, I just didnt have the cash to buy the ones I wanted, toss up between Firestone Destinations or Michelin LTX or such.

AFAIK after trying to balance them with a mechanic at the shop I tow for: The tires are SEVERELY out round. So much so that they took multiple weights and were hard to do and still vibrate. I just didnt get new ones b/c I barely drive the truck atm b/c of my work truck/van/tow truck.

B: The U joints gotta be on thier way out, I figure int he next 6 months I may change them. But I wanna see what new tires do first. If I change them, and I still have issues I am pulling the axles to check, nothing else seems to be wrong and my mech spent 2 weeks and looked it over top to bottom.

Course, I could have axle wrap...

Enter option C (which I dunno what the symptoms exactly are)

C: Possibly axle wrap on take off, the leaf springs are shot imho. The overload is flat, and the other leafs are nowhere near as round as they should be.

Any large bump will jar you. I havent found suitable bolton replacements other than add a leaf packs and progressive leaf packs, gonna call a spring shop and see if they can build me new packs possibly for a mild lift of 1" since it kinda sits low now.

It does make sense its axle wrap on take off, it feels like its wiggling along and at speed on the gas the vibe got better but is still there. If I take off easy you dont notice a thing, take off hard and bingo. Perhaps the softer springs are allowing the rear to tilt-thus my vibration? on take off of the wiggle and at speed, since less torque I dont feel it as much?

Another thing I noticed is if I brake stand the rearend wants to hop all over the danged place like crazy!

How are the clamps that hold the springs together? A couple of mine were bent and i had to use a BFH to close them again.

I will check as soon as it stops raining buckets outside.

I checked, each of the two spring clamps is on there, but the nubs arent even close to touching or being closed over the leafs.

The leafs are FLAT pretty much.. I think I found my problem.

FYI pictures of the springs: