Massey Ferguson 35 Deluxe electrical problem - Alternator or Voltage Regulator?

[Consonar]

My '62 MF35 Deluxe lights are dimmer and dimmer. Now engine has lost power (over half) and misfiring. Battery not staying charged either. How to troubleshoot if it's the alternator or voltage regulator?

Thanks.

 

[mitch becton]

can you post a picture of the altenator the tractor from factory would have a generator on it but many have been converted to alternator or possibly the numbers on unit would be most helpful