Alternator and External Regulator
 

This question is for a 1974 911S 2.7. The original alternator is an SEV Marchal - can this alternator be paired with a Bosch regulator?

I have never seen any limitation but in looking at some engine compartment decals, someone commented that the decal needed to be corrected to include the requirement that the alternator and regulator had to be from the same manufacturer. This seems strange but I'm asking before I plug it in and burn something up.

The original Marchal voltage regulator is an electromechanical device with solenoids and springs. Newer voltage regulators are solid state with transistors that replace the electromechanical components. I have used both the original Marchal and newer solid state models made by Huco. Both worked equivalently for me. Bosch should work the same as long as the three prong plug matches.

An old time electrical component rebuilder told me in his broken English (with a thick German accent) that the electrons don't care where they came from when they reach the voltage regulator, so any regulator with the correct plug orientation should work fine.

I was there to but a new regulator since my old Bosch one was acting up. He spent 15 minutes cleaning and adjusting my old one and said I should not replace it. I did buy a replacement to use as a spare, but the original one lasted for many more years before acting up again.

He's long since retired, but I still miss this old time service and advice! It's folks like him (& Eric Shea, Rich Paar, Henry Schmidt, John Walker, Paul Abbot, and many more out there that I'm forgetting) that make the old car hobby so much fun!