I'm running a fresh alt I bought from O'Reilleys Auto Parts. I took a RB25 alt I got from Venus, into O'Reilleys and the guy at the counter spent around 1/2 hr. searching the books, then went to the back of the store and came back with a match.
I swore I posted the info on the part number/ applacation, but I can't find it now.
There was a tiny difference on the casing where it bolts to the alt bracket on the block. I think I had to go pick up a new bolt that holds the alt to that block bracket, cause I think the spread is around 1/4 wider on this alt, so you need a longer bolt, and a few washers to shim it.... no biggie to me anyways....
Its still holding up fine and working as it should. I will try and locate the info tomorrow on the part number.