http://smg.photobucket.com/albums/v642/madele/?action=view&current=knocking.flv

sounds like you dropped a nut or small bolt down intake & its bouncing on top of piston.i would'nt be reving it up because it could be something on top of piston,or it could be a flywheel bolt but i doubt it.i did this once & it busted a hole in piston & took out a valve.i dropped a 3/8 nut in intake not a real big nut but did lot of damage.wish you luck

you say its in trans sure its not motor it just posted sound will travel

I put a screw driver to the motor no noise
I put a screw driver to bellhousing/trans noisy as hell.
Also if the motor is not at a low idle its quit my brother dropped a screw down his carb once it made noise as long as it was running if you reved it up it would get faster.

What tranny are you running?

87 t-5

What happens when you push in the clutch pedal ?
Does the sound stop or keep going ?
How well does it start ? (starter turn)
Could be a ring gear turning on the fly wheel or a bad throw out bearing.

Took the trans out reinstalled the old one with no reverse noise is gone took trans apart found input shaft needle bearings are shot along with the main drive shafthttp://web.camaross.com/forums/images/smilies/mad.gif
What is a good 5 speed trans I am sick of these problems I havnt even drove this car yet and its been through 2 t-5'shttp://web.camaross.com/forums/images/smilies/confused.gif

tremec time!