hi, I've got a 94 3500 van with 241k miles on it and have a vibration that gets very noticeable at 62 mph. I've had wheels balanced and the u joints are good, but I noticed that the driveshaft has a slight up and down play in it at the rear of transmission. Will that cause it? There's not a lot of fluid spray on the body, but the seal has a bellows on it, and I'm not losing trans fluid
any ideas?

 

Have you looked at the rear differential fluid or replaced the fluid? The fluid change is usually around every 50K miles.

Chrysler has a TSB that offers the use of 75W90 synthetic for better power transfer and better MPG. Redline sells the Mopar OEM fluid with friction modifiers. This fluid TSB is good on all Chrysler Corporate rear axles and not the Dana versions. However, in the Ford Truck forums, people are using the Redline in the Dana Spicer without issues.

Also, read the Chrysler TSB and note that the rear plate needs to use a RTV that is compatible with the newer synthetic fluid.

 

ball joints? although I thought they may have picked that up during the balancing, However I have had a friend drive all over the place with the same issue until getting around to fixing it.

 

I have a strange vibration also, did you ever find the problem? thanks.

 

I never did pinpoint it, I wound up replacing the rear axle seals,u joints,transmission mount and the transmission fluid. I think if I was going to do it over I would replace the fluid first.