I knew how lucky I was when my pre-35 came with this lined Bianchi holster. It also came with a proper Tyler adapter but I chose these target grips instead. If it's any help the holster is marked " BIANCHI #5B Kitgun PP" on the back.
My vintage Smith Leather brochure lists Model 21 - 66 only for the M-35, the "Blazer" my least favorite of the Smith holsters. I'd probably spring for a custom El Paso otherwise...
Mine was threaded on this Don Hume belt in the sage brush gopher town last (and next) week.