Shaking in 2nd gear...?

So yesterday I put in the OME rear suspension, finished the bumper, and greased the driveshaft u-joints. When I drove home from my friends garage at about 8.30, I noticed that when i was accelerating in 2nd gear from about 23-30mph, the whole truck vibrates pretty strongly. I have left it in 1st until about 25 and put it in 3rd at 25 and the vibration doesnt happen, so it has to do with 2nd gear.
The truck also vibrates when i depress the clutch when downshifting to 2nd.

Anyone know why this is happening? I was going to change the fluid today, tomorrow, or tuesday in the tranny, transfer case, and both diffs anyways, so will it help?

ideas are much appreciated.

 

Did you mark the original location of your U-joints in relation to the yoke on either the DIFF or the tail shaft of your trans ? , just the very nature of right hand torque (direction of drive shaft spin) will cause a U-joint to "seat" itself in the yoke flanges although slight, over time it could make a difference if not bolted back in its original location, vibration at different RPM's & road speed could happen, have your yokes checked for warping around the flanges , in any case I'd say you have a drive line alignment problem.

 

yeah a friend and i think it is the angle of the driveshaft to the pinion. it seens to be a little steep, so we may try to put wedges under the back of the leaf spring packs to tilt the driveshaft up and decrease the angle.
i will check drive line alignment as well though.