Alternator not charging?

Hello, I have the vehicle listed above Econo line E150 with an alternator charging problem. I have checked through wiring diagrams and as many people from O'Reilly's all the local auto parts stores, I've had a mobile mechanical credit without any success. At this time, I have uninstalled the old alternator to reinstall the new one at such time the wiring harness had vanished for the alternator. I'm not the one who ripped out the harness and therefore I have no idea where it went. I've had other people put their head in the hood looking for that Lucy harness without any luck at this point I tried to bypass and install the new alternator and use the field wire from the voltage box and wired up that way without any luck the alternator is not charging the battery still the car will start and run for a few seconds and then it turns right off. I haven't in a place where it cannot sit and it's going to be towed very soon if anybody could help me, I'm currently appreciate it. Thank you