Vincent Bach New York Model 35S Prototype?

I’m particularly intrigued by this New York Bach trombone—it’s one of the earliest in my collection and the earliest I’ve come across. With a serial number in the 1xx range, it dates back to the early 1930s, just when Bach was beginning to manufacture trombones. This model is equivalent in size to a modern Bach 36, featuring an 8″ bell and a .525″ medium bore slide leading me to believe it may be an early prototype for the model 36. It’s labeled as a 35S on the slide and retains all its original components, including a nickel silver neckpipe. Noteworthy are the subtle variations present on these early Bach trombones, such as different knurling and octagonal bracing and supports in various areas. These design nuances are characteristic of similar Bach trombones from this experimental period.