I am getting this clanking sound when I put it into gear or rev. or it downshifts to a lower gear.Also vibrations (steady) at 3500-and up. Drivshaft maybe?Tires are all bal. and I have new U-joints.
It is a stock shaft from my cutlass (84) originally for a 6 cyl.
Also the tranny was re-built and shifts fine.
just low rpm it clanks

You need to check the play in your rear end at the yoke, sounds like the ring and pinion may be worn or the lash may be off.

wouldn't it be more of a grinding sound if it was coming from the ring and pinion... only if the rear end was leaking i guess ???

hmmmm--Under heavy loads say around 3000 and up, when I stomp on it, I kinda smell what to me is gear fluid(we all know that smell) Maybe im burning it up?.No leaks and decent fluid.Could this be tied together with the info you said?
thanks for your input..But then again ...How would I be able to smell whats behind ,at speeds.....

If you are smelling gear oil( believe me, you can smell it inside at high speeds,ask anyone who has run short tracks),check your rear end after driving around awhile and see how hot the carrier is, also check oil for level and smell if it is burnt.