ALL of the cast iron parts, block, head, gear box etc. should have a date code. Like D 11 9 (with A=Jan, B=Feb etc, 11=day of the month and 9 being the year, like 39 or 49 or 59 etc. You can nail year of mfg. down with this code or get close. Parts cast near the end of the year would be acutally used for next calendar year truck.
