Vibration noise

[323driver]

I have a problem with my GTX tranny. When I shift in 5th, I start feeling and hearing pulsating vibrations above 2K rpm going at 100 km/h. I though it was the drive shaft but cruising at 120 in neutral doesn't make any vibrations. It sounds just like a bad wheel bearing but my bearings are new and by putting it in neutral at high speed, there is no vibration. When I put it in 4th at 110 km/h the engine goes above 4K rpm and screaming so it's hard to tell but it seems that there are no vibrations.

The noise sounds definitely like a bad bearing and it appears slightly stronger when I press on the gas than simply cruising down. Anyone have a clue on what it is?

[jay]

Output shaft bearing?

[323driver]

That's the one going to the rear? Wouldn't it vibrate when I put it in neutral at high speed as well though?

[jay]

Not necessarily. Go under the car and grab the driveshaft right where it comes outta the transfer case like you're trying to choke it to death (easy to imagine ain't it?). if there's any play at all, you need to replace those carrier beaarings.

[323driver]

ok thanks, i'll do that tomorrow. Anything else I should check at the same time?
The thing is that before the tranny swap, both front bearings were shot so I couldn't go above 80 as the vibrations were sick so now I don't know if it's the new manual tranny that is bad or anything else that was on the car before. Uggh, that car was soo poorly maintained, surprisingly never seriously hit though.

[jay]

make sure your trans and centerdiff fluid levels are where they should be...stuff should come out of the upper of the two fillholes.