I can give a little more clarification. The 396 was changed over to the 402 in mid '69, Chevrolet referred it as the "396" due to the marketing that was already in place for their engines. That is why you see "SS 396" '70 Chevelles, Camaros, and Novas, GM didn't want to change the marketing. Besides, SS402 doesn't sound right. In trucks they called it the Turbo-Jet 400, which is the big block name. There was also a Turbo-Fire 400, used in passenger cars, that was a small block. By the way, the 454 came out in '70 as a replacement for the passenger 427. The tall deck 427 was still used up to the late '90's, as was the 366 big block.
The 402 was used in trucks to '72, the 454 was introduced in light trucks in '73. The small block 400 was used to '80.
