Product Search | Delco Remy | Remy
Use the link (remyinc.com and select e-catalog) and you can select the year, car and engine and see what starter or alternator they make for that year now. These choice probably mirror what was available back then and you can try and find a junker from that model, etc.
I was using the application search tab to get an idea of what cars offerred the 12si and what amp model was used for what. Then when you pull up a vehicle select say the 78 amp model 12si. When that page loads there is a list at the bottom by make and you can see other models from GM that used that same alternator.
It was helpful for me and maybe it can help someone else find the 78 or 94 amp 12si for example and what cars to track down.