Here is a collection of documents which provide "evidence"
of just how the Streamline models looked when came from the factory,
and changes that occurred during production.
Parts List for Streamline (pdf, 6mb)
Parts List for De Luxe (pdf, 5mb)
Care and Operation for Streamline and Deluxe - 1929 (pdf, 9mb)
Print single-sided, then trim to 5" wide by 6.5" high
Excelsior-Henderson Service Bulletins
Excelsior-Henderson Sales Brochures
Ballak & Company (serial number list)
Excelsior Henderson Restoral Society Documents
Steve Blancard (Splitdorf information)
Of course, there's no such thing as absolute proof. Factory documents sometimes contain inaccuracies, or fail to note running changes on the production line. Some of the experts' memories have grown fuzzy with time. These bikes were produced seventy years ago, so we can't just go to the dealer and examine a new bike. The best we can do is to present the best documentation we can find, and draw the appropriate conclusions.