Acura Repair: cracking noise - spun bearing?, metal needle, stethoscope

Question
I just bought an 1991 integra with a cracking noise. I replace the clutch which was needed, and I put back the transmission back on without the axles and still makes the cracking noise. The noise does not sound when it's in neutral at all times, but when I engage any shifts it will make a cracking noise. The highe the gear the faster sounds the cracking noise. I've read a few forums and I hear the term "spun bearing." I read it's either the train-e or engine. Can you please advice me which bearing is it referring to. Thank you, I greatley appreciate your advice.
From,
eN

Answer
I don't think it's your Crank bearing as the bearing spins at the same Rotation Per Minute (RPM) at any gear. If it's getting louder the higher the gear it probably is your transmission. It could be that something is rubbing in the housing where your clutch is. This is what I recommend, buy a automotive stethoscope, it has a long metal needle, you take that and place it on your tranny housing first then your tranny then your engine. See where the you hear the cracking noise the most that way you can determine what it could be.

Thank you,
Daniel