Wow, thanks for the quick answer William, a Mopar Nut is what I need. A transmission was advertised on eBay as a NV3500 from a 2001 2WD Ram with a 318 (5.2). His story, and I've spoken to the owner on the phone, is that he decided to tow with the truck, then found out the NV3500 was insufficient strength, so changed to a salvaged NV4500 from a wrecked '01, and still has the NV3500. Best I can make out from the picture, it has these numbers on what appears to be an integral (or attached) bell housing: TTMTT31A1305 and PP2108199AD.