95 T100 2wd. 3.4 V6 with A340e auto trans. 462k miles. My truck had been making a rhythmic tapping noise at idle. It only happened at idle and only when warmed up. I first though it was a rod knocking but on further listening, it was coming from the trans bellhousing. Due to health issues, I parked the truck at my Dad's and drove another car for the past eight months. Sunday, my sons and I pulled the transmission and removed and replaced the flexplate with a good one from a junkyard. There was a series of connected cracks spanning about 180 degrees around the center of the plate. I haven't gotten everything connected and started the truck, but I'm convinced that the cracks were the source of the noise. It seems that the plates from 95 to 97 are affected but only with high mileage, such as mine.