- What is positraction?
- It's a limited slip differential which distributes power equally to both the right and left tires.

9 seconds sound clip from the My Cousin Vinny movie soundboard.

You can hear this line at 01:46:49 in the Blu-ray version of the movie.

Quote context

[...]

- Would you like me to explain?

- I would love to hear this!

- So would I.

- The car that made these two equal-length tire marks had positraction.

- You can't make those marks without positraction, which was not available on the '64 Buick Skylark.

- And why not?

- What is positraction?

- It's a limited slip differential which distributes power equally to both the right and left tires.

- The '64 Skylark had a regular differential, which anyone who's been stuck in the mud in Alabama knows, you step on the gas, one tire spins, the other tire does nothin'.

- That's right. (5)

- Is that it?

- No, there's more.

- You see when the left tire mark goes up on the curb and the right tire mark stays flat and even?

[...]