Regulator. I believe I see 2 wires on the B (battery) terminal and none on the A (armature) and none on the F (field) terminal. It is common to only use the B terminal when converting from generator to alternator. It also means the truck has been converted from a 6 volt to 12 volt battery. It would help if you would share any information you have about the wiring and any electrical updates.
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
