No serial number on the case or movement.
I'd guess that someone has smoothed down the serial number and Bulova datestamp at some point.
Model is the Gedney, like this one.
I like this one. We have had numerous debates over this model. All examples in the database so far dated 1956 or earlier have a stainless back and those dated 1957 have a RGP back. Interesting that the case back presents no serial number or other markings but is marked properly on the inside. It almost looks to me like the s/n and other info was polished off based on the appearance that the back edge on either end is missing the "step line" with a slightly different radius. I wonder if perhaps the engraver did this to have a clean slate to embellish? Noting this inconsistency and basing date on movement
1957 Bulova Gedney