The Mighty 396...NOT!

No, the 396 was the 396 from 1965 until 1970. Then it became the 402. The story I always heard was that someone set the boring bar by accident at .030" from a 396 standard bore and bored several hundred blocks over. Thus the 402 was born. The 396 bore was 4.095 and the 402 bore was 4.125. The 396 was made from 1965 to 1969. The 402 from 1970 to 1972. They were two different engines, although they were marketed as the 396 still in the smaller cars, while they called it a 400 in the big cars. They actually called it the 402 in trucks.

http://en.wikipedia.org/wiki/Chevrolet_Big-Block_engine#396_and_402