I have 2 cars with TKO's, the one in the chevelle makes some slight rattling noises in 5th gear with just slight load. If I let off the gas it goes away. Its smooth but still makes the light noise. What could this be? :confused:

I don't know on a TKO in particular, mine doesn't do it. But I had a Ford truck with a ZF 5 speed that did that exact same thing. A transmission is part of the drive train system, comprised of the motor, drive shaft, axle, etc. A system always has resonant frequencies, where the frequency if excited, is perfect to get everything rattling. In the case of that Ford truck, they put a rubber suspended steel ring on the driveshaft to try to change the frequency and damp the vibration. It doesn't hurt anything, it's just annoying. If that's that issue...

Its a little bit of a clatter though..

Had a ZF in a Vette that would do it, most did. It was more apaprent when a lightweight flywheel was used, especially an aluminum. There was no cure but no problem that caused it either.

What does the man. say?

maybe its the clutch and you dont hear it in any other gear because they are 1:1 or greater