Bob --
I don't have the exact answer you're looking for -- and was hoping someone would answer so I could see too.
So -- here's what I did...
First, I wasted a lot of time searching the internet and the local auto parts stores. Without knowing the year/make/model of the car which used the unit we want, you can't find it! I still don't know this information. Actually, it may not exist in nature, in the exact configuration we need, specifically, with a v-belt pulley on it. So I went to Schelen Auto Electric in St. Paul. Specialists! They actually know what they have, and rebuild them on the premises themselves. I explained what I was doing, and what I wanted (the smallest diameter Denso alt, 40 - 50 amps.) "Dave" led me to the shelf where a hundred or so Denso alts were in plain sight. He picked up a little one and said, "This is what you're looking for." It had a flat-belt pulley on it, so I asked if I could have it with a v-belt pulley. He reached into a box, produced a pulley and said, "Sure." He painted the pulley, installed it, tested the alternator and then took my money.
Somebody in Mass. has to be plying the same trade. Good luck finding them!