There is no computer to blink out codes, so there is no diagnostic port to connect to the non-existent computer.

 

Sure it might not be present-day technology but at least I could “blink-out” my codes.

No, it's even older than that, as Mark said. When you have a symptom you can't diagnose, post a THOROUGH description of it, and other members familiar with trucks that old can probably guide you. But there's no telling what details they might need about the truck's current condition & history, so you should put ALL of that into your signature now (as I mentioned in your other thread).