hopping and vibration

[mattl140]

took my 305/55r20s with 20x12 -44 tires off and put my other tires and rims on and it drove nice no hopping but i did notice a slight vibration so i jacked the back up and put it in drive i noticed the vibration and the driveshaft seemed like it was warped like wobbling.

 

[dmistak617]

So what's the solution? My 6.4 is doing this


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[fastersteve]

I have the same problem with my Excursion. Hard vibration from 40-45 and again 80-85.

Done u joints and re-balance of driveshaft twice. Does it on stands without wheels and tires, so that's not the problem.

I read somewhere that the drive shafts are packed with cardboard, could that be true?