Vibration @ 35'ish

I had a similar problem in my Nissan, it was caused by my center carrier bearing on the driveshaft going bad. Don't know if your truck has one, plus you said you had the driveline looked at but this was my problem. Mine was due to being lowered and the driveshaft wasn't shortened until after the bearing went bad.

i would say a u joint b/c when you let off the gas it takes the so call twist of a bad u joint out and lets it vibrate and also i would say check the pinion angle

Dont know how to load pics to you guys to see what exactly is going on. But, I just noticed that the upper bracing for the drivers side lower control arm (on the inside of the frame) is apart from it's welds. The damn welds broke! It now sits out about 3/4". I'd imagine this can cause some problem...would it cause the vibration? I'm gonna replace the u-joint for shits and giggles. See what happens. Anyone care to tell me how to get it out?

Btw, this morning I was in 1st and felt it pretty bad at around 4000rpm's then got into 2nd and felt it bad, regardless of pressing the pedal or not.

dude my toy pulled that shit on me a couple times. one time the radius arms broke. and the other time my wheels were out of balance.

A missing c-clip in the u-joint and a missing nut on the lower steering linkage. Thank GOD ball joints are pressed in so well! I've driven that thing 30 miles or so, tryin to figure out where the vibration was comin from....dangerous!!! Anyhow, any of ya ever need a spare c-clip, given the fact that I found none locally (not even salvage), let me know. Peace!