Its a tough call and I will say that I once used a troubleshooting guide to troubleshoot the ignition system on a Dodge truck I think it was a 77 Dodge. The tests came back that the module was good but no spark. I then decided "it has to be the module" tossed one in and it started right up...you may be right that your supposed good regulator isn't good. the thing is youll spend time shooting wires etc when it is a part.