Transmission Vibration

[bobcostas]

Hey Dudes!

I posted a similar thread under the drivetrain forum to no avail, and now it seems it may be worse (maybe)

I have a four speed standard on my C10. When its idling with the clutch engaged, it seems to make an oscillating rubbing noise and the stick starts to shimmy. I was thinking the clutch might be bad, but i have never experienced a symptom like this. Now it seems 3rd gear is a little rough. there is a shudder at some speeds. it also presents itself around 40mph in 4th.

Do you guys have any thoughts?
I changed the fluid this AM (the old stuff was also red, which doesn't seem right. I put in 90wt)

thanks a lot dudes.

~BC