Charles,I originally was going to diy the Amtrans, wiring of MKI volume transformer different than MKII, so not so straightforward. Israel did send me wiring illustration for Amtrans to MkI trans. Ultimately decided I wanted the upgraded transformers, so sent to Israel.
The proper Amtrans are the single gang switches at Partsconnexion, the other they show is stereo switch. I can't give you any info about the transformers, I'd have to tear apart quite a bit to possibly get part number and manufacturer, may be proprietary part as well. If you decide to not diy, perhaps you could send control chassis only, save some shipping cost.
As for going off topic, yes, sorry, The problem is Audiogon no longer allows private email.