my understanding is ( could very well be wrong) that FORD/ Motorcraft does not make a brand new alt for our trucks.. If its a FORD/ Motorcraft alt then it has been re-manufactured ... which is good either way because you should have the proper voltage regulator in it. The inferior voltage regulator in other re-mans will cause the Battery light to come on no matter what the output voltage is. I have seen this at least 10 times now... its hit and miss. Either that or your cluster is going bad.. another common item to take a crap.

 

so, this is whats been done

took truck up to the auto electric shop, then had the tech test his way with his equipment, the same guy I bought the alternator from
he said everything was good, but we pulled it anyways and he put a new, old stock fomoco voltage regulator in it
same results, battery light still on
for craps and giggles he wanted me to bring truck to local napa and have them perform the tests on alternator and battery
according to them everything is still good, even though the battery light is still on


So, cleaned up all wires and connections going to battery, checked all fuses in PD box under hood.
next step is to book an appointment with a ford shop