I just picked up a 93 80 with 240K on the clock for cheap, knowing that it had a few issues but overall was in pretty good condition. Motor is strong but the Birfields click preatty bad . I am very familiar with Birfs, but there is a very loud hum when on the gas. It doesn't change pitch when the trany shifts, but gets louder as speed increases. The noise seems to com from the front or center of the cruiser. i thought about pulling the rear drive shaft to eliminate the rear end from the issue. Any other suggestions as to tracking this one down.