The difference betw. standard/tourer alt and the I/S alt is the capacitor on the back. I believe you can scavenge the cap. from your old one if your new one doesn't have it. So, no matter which type of Valk you have, no worries with the "standard" alt.
I don't know about the casing on the high output alt., so I can't speak to that.
Mark
Grego
You would be wise to listen to Rocketman about alternators. He is the expert on alternator replacement. (not by choice).
RainMaker