A 3-wire pump uses 4 wires because they added a ground wire back in the 90's. A two-wire pump uses three for the same reason. The 4th wire (or 3rd) is just a ground.
You should be fine with the franklin box, but they can't tell you that. Something about CYA. I would at least try it and see.
You should be fine with the franklin box, but they can't tell you that. Something about CYA. I would at least try it and see.