To all who responded--First, I was wrong. It is a 3 brush gen. The head of the set screw has been broken off and painted over so couldn't tell from the outside! Secondly, had time today to open up the switch box and found someone had "reworked" the internal components. The IH 4 position switch has been replaced with one like AC tractors use! Cleaned all contacts and terminals and discovered that by pulling out the light switch to various stops, the charge rate can be controlled. Everything is working fine and everyone is happy. Thanks to all for your help. PS-- Performed the suggested test to determine the A and F gen. posts--So am disregarding the markings.