Voltage regulator size

Hi I have 2 regulators come in the box of bits with the bike
One is larger size than the other but both have the same wire connections

The smaller one has a sticker from a supplier with KZ1300 79-81

The larger one wiring all been tampered with with scotch locks etc

My bike is 81 A 3 with the side engine pick ups

Can I use the smaller one ?????

If you can mount it to the frame you should have no problem, Pick-ups and Ignitor can't be interchanged. Honda tend to do a universal Reg/Rec so foresee no issues using the smaller one. Maybe one of the tech boffins will say different but I doubt it

I seem to recall a conversation about this once before regarding the 2 regulators/rectifiers related to the 82 model with the 2 alternators. I thought we figured out that one of the units was a master and one was a slave??