Driveline vibration that has been plaguing me all month finally showed itself.
Transmission exploded, motor is junk. Not apart yet, but broke a rod for sure by the sound of it.
Car was handling great, was running around in 5th place after leading the first 7-8 laps at 3/4 throttle to keep my eyes from vibrating out of my head and she blew with 5 to go.