bad vibration 65-75

[agidius]

I have a 1996 Chevy suburban 4x4 K1500 6.5TD.

between 65-75 there is a horrible shaking. Bad enough that anything in the cupholders WILL be thrown out of them. I do not feel it in the steering wheel. between 60-65, the panels rattle, but my teeth don't.

I have run out of ideas.

I have changed:
all wheels
all tires
all shocks
rear axle shafts

I have tried:
with/without rear wheel spacers
inspect all front end parts
inspect u-joints

should I change the u-joints anyway??
should I take the driveshaft off and have it measured??

what else can I try??

[a5150nut]

Hows the carrier bearing on the drive line?

Does it continue if you let off the loud pedle?

[agidius]

no carrier bearing, just a long driveshaft.

pedals have no influence on it, only speed.

[bmoeller]

Similar problem on my '97 required on the vehicle tire balance job to solve. Local NTB shop machine just could not get it solved in four tries and finally sent me to another shop that specialized in trueing and on vehicle service.