While in Overdrive, and after the Torque Converter locks up, I have this strange rattle at around 42 mph during light acceleration or when coasting with no acceleration. (It's like a metal clanking noise). When I had the 383 Stroker built, a new internally balanced TCI Flexplate was installed along with a YANK SS3200 TC. The 700R4 Transmission is a GM factory refurbished unit with around 5,000 miles on it since it was installed. I've checked everything in the rear suspension, and all components are tight. Over a year ago, I changed the gearing with a Yukon 3.54 Ring & Pinion, replaced all u-joints with the Spicer Brand and also installed a new balanced Driveshaft. At 42 mph, the rattle is present about 50% of the time. However, if I'm in Drive (not OD) it will not make this rattling noise at any speed. Dave at YANK suggested that there wasn't anything to rattle in the TC and is thinking possibly the Flexplate. Since the noise is only present around the 42 mph speed during light or no acceleration, I'm at a loss as to what this could be. I would think if it was the Flexplate, the noise would be present all the time and get worse when accelerating. Does anyone have a direction they could possibly point me in? I'm just trying to prevent the expense of shop looking at the Flexplate / Torque Converter area if it might could be something else. Thanks!