Hi Gary.
The correct mag. would NOT be a BT-H MC2, but the one you have should be perfectly OK unless you are a perfectionist, in which case you should look for a BT-H M2-G2. These have a horseshoe shape magnet and alloy plates to close off the open sides of the magnet. Those plates have the BT-H logo pressed into them.
Not all Super Squirrels had the M2-G2 from new, as bikes ordered with an electric lighting set would have had either a Lucas, BT-H, or occasionally a Bosch combined magneto/dynamo unit.
The factory had cashflow problems for decades and would fit electrical equipment from whichever manufacturer would give them credit!
Over the years magnetos from Dixie, Fellowes, EIC,Lucas,BT-H,Bosch, etc., all were fitted. As Bosch had a factory in New York at one time you might be able to find a Bosch ZA-2 more easily, and they are VERY nice mags.
Regards, Brian Marshall
