I am thinking off the top of my head maybe a '78 Camaro engine? That is a Norwood Ohio VIN Derivative for a model year that ended in "8". They built Camaros there and they never built Vettes there. Can't be '68 because the 3-digit engine suffix was not in use at that time - they were using 2-digits in the '60's. The 3-digit "CHC" engine build suffix is for a "car engine" (not a "truck engine" or it would start with "T") built in the late 70's. You might check in the 2nd gen Camaro web sites to see if the "CHC" engine suffix works out to be a '78 Camaro. Thats my best guess without working up a sweat.