What Happened?

Back in 1978-79 I had a '68 GTX that the negative cable went bad,
it drove me nuts, I parked the car on hills or small inclines a popped
the clutch with the car in 2nd gear for a month; till I figured it out.

The outside of the cable looked ok, except near the engine block,
where the vinyl jacket was swollen up. It was all corroded underneath. :(