how's the harness on the engine? there's a red wire that has to have 12v with the key on at the alternator. the 81-88 engine harnesses come apart in places you can't see. if you look at the firewall connector, you might see the insulation flaking off. same goes for the alternator and oil pressure switch. if that wire's broken between the firewall and the alternator, no 12v, no charging. good luck, chuck.