No need to apologize. You are brand new to this forum and it takes some time to get adjusted.
In looking at the wiring diagram on page 66 of this manual
http://www.manuals.casecoltingersoll.co ... marked.pdf
it would appear that you have to do the following.
1. First .... remove the positive cable from the battery and set it in a spot where it cannot touch the battery terminal accidentally. This is a safety procedure.
2. The wire going between the F terminal on the regulator and the F terminal on the Start/ Gen is no longer needed. Disconnect both ends and tape them off.
3. The heavy wire going from the starter solenoid to the A terminal on the Start/ Gen can be relocated to the terminal on the new starter motor.
4. The wire going to the L terminal on the regulator can be removed from that terminal and installed on the B terminal of the regulator. This will put power directly to the B terminal on the key switch and still leave the harness and the fuse intact.
5. The wire going from the underside of the regulator to the solenoid should be disconnected at both ends and taped off.
6. The new-to-you engine will have two wires coming from the stator under the flywheel and into a connector. You need to have the regulator/rectifier that plugs into those wires along with the connector the regulator plugs into. You also need to find a suitable spot to mount that regulator and make sure that the body of the regulator is grounded to the tractor's frame. The red wire exiting the connector must be attached to the "I" or ignition terminal on the key switch, as shown on page 64 of this Parts Manual.
http://www.manuals.casecoltingersoll.co ... marked.pdf
That's as simple as I can make it so you don't have to butcher your existing wiring harness nor do you have to make a new harness. The existing regulator can stay right where it is because it is disconnected from the electrical system and is used as a terminal block to join two wires together.
Welcome to the group. Glad to have you here. Please...... read the STICKY messages at the top of each forum that say "READ ME FIRST BEFORE POSTING" . Those will help you understand what each forum is for. :thumbsup: :trink: