Those are amperage ratings. Most alternators were 37 amp, with 834 being the most common. 837 is the same alternator with a deep groove pulley (for L72, L78, Z/28)
843 was a 63 amp unit used on air conditioned cars.

 

If I replace my 37 amp with a 55 amp, will I need to replace anything else such as the voltage regulator?

 

No.
But what problem are you fixing by changing to the higher rated alternator??
As long as you don't have electric engine cooling fans added on, the 37 amp one will be fine, just like it's been all these years.

 

In the process of restoring my engine compartment, I bought a new Delco 55 amp from Rick's because I thought my 37 amp was not original. A few things led me to think this but mainly because the fan and pulley are black as opposed to the being silver cad plated. I got hasty and just assumed it must be a rebuilt unit. I then checked the numbers, which is what I should have done in the first place

, and realized it is the original. My original looks real nasty but I am going to send the new one back and get the original cleaned and bead blasted.

 

Send it to Pirkle to get restored. It will be perfect when it comes back.
Beadblasting will change the finish....

 

Thanks Kurt. I just contacted him and am going to send it to him.

 

One question: I take it you confirmed the date code was correct for your car?

 

Can I get more info On Pirkel? I need one done. Also need work done on electric window motor and rear defrost motor.

 

Try www.JohnPirkle.com .

 

The date code on my alternator is D911. I assume the D means April? Seems right for my May build pace car.