Vibration from rear axle?

[robbie]

I have a 1996 Taco, auto,v6,lifted. Recently I have had the rear pasenger side axle seal replaced. Done at a dealership. Since I had the work done I have been experiencing a vibration in the truck at about 1800 to 2400 rpm. I took it back and they said it was drive shaft bearings. I had those replaced, still vibrates. Then they said it is a bent drive shaft, I had that fixed too, still vibrates. Could there be something with axle or rear end that might have been replaced incorrectly that would cause a vibration? Even a drum being put on wrong??? The vibration did stop when the rear drive shaft was out of the truck and i was only using the front wheel drive. Also the vibration stops when driving and I put the trany into neutral. Any thoughts on this would be appreciated , thanks!!!!

[Hoodlum]

Look where the slip yoke goes into the shaft if they took it apart there's a chance that they didn't line up the "balance marks" there should be a yellow mark on both the yoke and the shaft if they are NOT lined up your drive shaft is out of balance.

[robbie]

Thanks for the reply Hoodlum. The truck is back at the dealership now. I ask the dude to have a look and make sure the marks are lined up, you would think they would know that but I have my doubts. They have suggested that it might be the center u joints that connect the two half shafts together. This is getting expensive guessing and replacing parts that are not causing the problem. I will have a new drive line soon at this rate.