The engine serial numbers or "dress" #s are stamped into a pad on the passenger side immediately aft of the distributor hole. You may have to shoot it off with some carb spray. I haven't had any luck posting my serial numbers and the casting numbers will only give you a range of '63 to '73, for instance. LMC Truck has a short list in their catalog of the 2 or 3 letter suffix codes and what years they correspond to. But I have a known '68 original L6 292 block with the suffix -XAE. Not on LMC's list, so it must be a figment of my imagination.
