Alternator model question

Kind of a dumb question...but regarding alternators for the disco: one for the 3.9 and one for the 4.0. Both pulleys have 7 groves I believe. I have a reman one for a 3.9 sitting around but have to replace one on my 4.0. Why would they not be interchangeable? Is there anything preventing me from using my reman 3.9 alternator on the 4.0 engine?


thanks for the help.

Yeah, it will work on the 4.0.

thanks Tom!

So, did it work out OK?

Yes, it worked out fine. The issues that I was experiencing such as pulsating electrical equipment (really noticeable with headlights and dash lights) have disappeared. I had visually checked grounds but they seemed fine.

So, I guess the 3.9's for with the 4.0's. At least for me.

Dave