Last week I had a costly incident at TMP while running my Chevy II. LS Turbo combo with holley dominator efi. T400 w/ and gear vendors. The car has been running the current configuration on the street and track for 7 years. This issue showed up as I let go of the trans brake button. The car left as per normal (1.25 ish) and just about at the shift point it started to rattle the tires (275 pro on reasonably decent prep) so I short shifted into second and instantly the rear end locked up solid. I brought the car to a sliding stop and shut it off. We ended up having to pull the car to the trailer with the rear tires on skates, and proceeded to drag the car into the trailer. Once I got the car home, and unstrapped it, I found whatever was locked, to be unlocked, and we rolled the car on to the hoist. We all assumed I had broken the rear gear, so I disassembled the rear, only to find it mint. We then pulled the trans and sent it off to Hutch for an inspection. When I got around to looking at the datalog, I didn't find anything abnormal. The green light for the TB being on shows on until I release the button, and ds rpm starts to show. I see where I started to loose the tire, shift, and then we broke. The TB light never comes on in the datalog after I released it. Got a mssg from Hutch, and he told be the TB had come on, and thats what locked up the driveline. Both Hutch, and Greg Powrie who tunes the car believe I have a flyback voltage issue, even though I have the holley FB voltage attachment wired into the trans brake circuit. I DO however have the reverse light switch tied into the TB button so I don't have to depress the button to back up. Is the flyback coming from there? I can't say, but this has never happened since the car was built, with not changes to the set up. Now, can I add a toggle switch inline between the reverse light wire, and the TB connection on the trans, to help protect against flyback voltage? Does anyone else have experience with this sort is scenario?