The FSM cites 4 possible alternators on a '77 280Z (a 40amp, 50amp, and 2 60amps), but I cannot find any external markings on my unit, which I believe to be original.

So, I am wondering how I can tell which unit is installed.

I would appreciate some enlightenment.

Thanks.

 

Just get the 60 Amp and be done with it. 

11 hours ago, ensys said:

The FSM cites 4 possible alternators on a '77 280Z (a 40amp, 50amp, and 2 60amps), but I cannot find any external markings on my unit, which I believe to be original.

My copy of the Factory SM only shows one.  Are you sure you're not looking at a Haynes or Chilton manual, or a generic all years 280Z manual?

And Nissan puts stickers on almost everything.  Since the internals can be different I don't think that they'd use a cast-in mark.  1977 should be an external regulator, last year before the internally regulated alternators.

13 hours ago, w3wilkes said:

Just get the 60 Amp and be done with it. 

The 60A model is likely internally regulated. If the OP installs it without jumpering out the external voltage regulator, he would be introducing a new set of problems.

I'm with Zed Head... I only see one listing in the FSM for an alternator. What am I missing? were there different options for 77's somehow?

I know it doesn't really matter, but I'm just curious.

 

Well, I stand corrected.  I actually gleaned the list of alternators offered from the Parts Manual. As this is at odds with the FSM (as implied by my Service Manual and ably illustrated by the excerpt above), I wondered about the possibilities of unknown substitution.

 

 

 

 

The parts manual lists a cold weather 60A alternator with part numbers 23100-N3302 and 23100-N3303. I doubt you'll find rebuilt versions of these in American part stores. You're more likely to find a rebuilt version of 23100-P3006. This is the internally regulated alternator.

So do any of our Canadian brethren have a cold weather alternator? They would have been in a 73-77 model year car.