My caddy had a lot of noise from under the hood. I replaced the a/c compressor along with a new clutch to get rid of that noise. Now It seems I can isolate the other noise to the transmission. At idle, with the a/c running, you can place a hose on the underside of the transmission, and hear a "rattling" kind of noise that seems to be affected by revving the motor, or just taking off. The tranny is a T400, with about 18K on a rebuild. The motor is a 305. Any ideas?