92 k1500 vibrations

I have a 92 K1500 4x4 with a 350 tbi and have been having serious vibrations at 55-75 mph when accelerating. It sounds like a dieseling semi. Tranny was rebuilt last year. Don't know where to begin. Any suggestions?

is it downshifting properly when you stomp the gas at those speeds?

U-joints - Allignment - Wheel Balance will all cause vibrations, I would check those first. Also, though very rare, off balance driveshaft could be the culprit.

Man I have a 1991 Chevy k1500 with 2 month old tranny,freshly rebuilt, and I am having the same exact problem, am also having vibration between 50-70 mph under accecleration. Checked driveshaft, u-joints wheel balancing etc. put truck on stands, put in drive and pushed the accelerator some, still vibrates, with driveshaft removed!!!!!!!! Any ideas ???????Please help!!!!!!!!!!!!:banghead: :banghead: :banghead: :banghead: :banghead: :banghead:

I have same problem, but it does it between 40-50, and also in 1st gear. It started after I did a good burn out. any ideas?