Chevy mixed their big block and small block sizes as well. The first big block was a 396, but the largest production small block was a 400. When the 400 did come out, I believe GM bored out the 396 to make it a 402 as to avoid the confusion of a big block that is smaller than a small block. And the biggest big block of all, tied with the tall deck 427 was the tall deck 366 which was also the smallest. Instead of using shorter connecting rods to make room for a 4th piston ring, GM just raised the deck height of the block, making it taller and wider than passenger car big blocks so it was the biggest on the outside but the smallest on the inside.