Fatweed, the 366 is a downsized big block engine found only in mid-size and larger trucks. There was never a passenger-car or pickup application, to my knowledge.
I can remember when the big block engine first came out, and it was originally a 427, for racing purposes only. It was known as the "mystery engine" because nobody had seen a Chevy big block before then except the 409. This one had straight-sided valve covers, not the scalloped ones. Junior Johnson dominated the 1963 Firecracker 400 race at Daytona, until late in the race when the engine siezed up. Within a few laps, every big block Chevy had failed. Post-mortem teardown revealed twisted-off oil pump drive shafts on all of them. Too much oil pressure! The first production-car big blocks came out as 396's in the 66 Caprice.
Jerry
