Hiya JoeBob,
I've had this type of problem before, but not in a Pinto.. I've run into this on a 70 Chevy C-20 & some VW-Air-Cooled's I own.. I ended up in most cases simply rewiring the whole thing & adding the proper connectors where needed.. (which isn't near the problem of cars like a Pinto, VW, etc because you don't have to be concerned with all the computers that now control everything in the car. Ya just have to have a good, working knowledge of vehicle electronics, etc.. or find/pay someone that does. Sadly, it may be something that we all simply may have to look forward on vehicles of this vintage, they now call 'em "Survivors" for a reason..).

C. M. Wolf