I had the pleasure of working with Joel a couple of times ( running sound ). I asked him about the sound of his accordions on his different recordings and he told me that the sound is produced in the studio with effects ,in an effort to reproduce the "old time" sound.
So , I believe the answer to your question is really a mute point. It doesn't really matter which brand accordion he used. The sound was produced by the magic of the studio electronics.
Jude

Thanks for the info.

I am one of those folks who likes the sound of the bass reeds. In Jo-El's recording they are very rich and not covered up by the rest of the band.

RPr