Rear Tires Suddenly Lock Up Going 65

I had the same thing happen years ago with a 4 spd big block 67 Belvedere.

It turned out the big block made enough torque to, over time, loosen the pinion nut, which allowed the pinion to drive too deep into the ring gear.

It stopped me dead in my tracks. Put it in reverse, and it loosened pinion and allowed me to baby it home, but any hard accelleration caused the pinion to "over" engage, wedging the gears so tight they would stop the car...but, it didn't happen every time. Every 3-4 hard launches created the same result, and that's when I pulled the drive shaft and found the pinion nut was very loose.

Let us know what you find.

Southernman