Really? I've never heard them. Here's how Chevy marketed them. The 396 before 1970 was a 396 in every passenger car and light truck. From 1970 on, they were the 402. The reason for the increase in size was because the then new to the scene small block 400 which had a bore size of 4.125". Rather than continue to make piston ring packs fir the 396 (4.094" bore), Chevy smartly bored the 396 .030" over to 4.125 to keep from making two separate ring packs. From then, all the passenger cars were still marketed with the 396 engine, even though it was a 402 and the trucks were marketed as having the 400 even though they had the 402.
And your imagination is good. Chevy never once marketed the 402 as a 400 in cars.
At least not in America.
