My 1990 astro has a mystery vibration, the rear end has been completely rebuilt, along with a new, yes new driveline....on a costly trip to Disneyland last August, but yet still has a vibration, the tires are new and have been balance, rebalanced and balanced again but still vibrations....The vibrations occur at 60 mph and appear to be from the drive train not front end.
Any suggestions?

A description of when the vibration occurs and where you feel it comes from would help immensely.

A description of when the vibration occurs and where you feel it comes from would help immensely.

does the vibration occur when you accel or decelerate?
do you feel it in your bum or in the steering wheel

Both, Its continuous after and before 60mph, its not in the steering, and appears to be from the drive train, I had the work perfomed ( driveline and new rear end assembly and axels) at a driveline specialist in Vancouver Washington on the road to California...
Could it be possible that it is the torque converter?

may be a bent rim or even a loose wheel.
could also be a u joint starting to go bad, may seem tight but u won tknow until u take them apart and look at the needles
i had the same problem, turned out to be a little of 2 things, bent rim on right rear and and rear u joint had a few needles that were bad

My 1990 astro has a mystery vibration, the rear end has been completely rebuilt, along with a new, yes new driveline....on a costly trip to Disneyland last August, but yet still has a vibration, the tires are new and have been balance, rebalanced and balanced again but still vibrations....The vibrations occur at 60 mph and appear to be from the drive train not front end.
Any suggestions?

It could be the water pump, or the thermostatic fan. Have you checked the wheel bearings?

Yves.

I'd get the u-joints replaced and have the driveshaft balanced. It could also be a bad transmission mount as well.

If you are capable I'd do some of the diagnostic work yourself before taking it to a shop and throwing dollars at the problem.

I've already had the ujoints replaced with the new driveline, and all the wheels and tires have been checked and rechecked, however I have not considered the clutch fan or water pump.....

I guess that will be next...

Thanks everyone!

You may also find that your driveshaft is out of phase.

Remove it from the rear pinion yoke, rotate it 180* and re-install. Then see if your vibration is still there or is worse.

Also I still recommend getting the driveshaft balances.

I've had a similar problem with my 02 astro, and beleive it or not it took over a year to find the problem.
It turned out to be a tire (which was new) that had excessive runout, (out of round),
Take your van to a tire store that has a balancing machine that measures road force and also can check for out of round conditions of your rim and tire, most shops do not use this type of balancer.
I went through U joints, trans mount, check for torque converter clutch, wheel bearings, fuel filter, shocks, and having the wheels balanced and re-balanced many times. The only way I was able to pinpoint the problem was by having them checked and balanced using a road force balancer.
You will know if the machine checks for road force if the black cover that they put over the tire on the balancing machine has a wheel in it that contacts your tire when it is lowerd.