Case back:BULOVA,M9,10K RGP BEZEL,STAINLESS STEEL BACK and serial # Inside case back:2057 stamped in ink 11AF 17 jewel movement is dated N0 Dial has applied gold numbers and hands with subseconds dial and BULOVA name Crown is signed BULOVA.
So there's lots of ads for different variants of Senator through 1966 in the newspaper ads forum. The Spring 1964 cumulative section of the price lists shows many variants. The commonalities in all the ads for variants in this period are sub-seconds, 17 jewels, and non-round cases. Some Date Kings look like Senators, but with the date function.
Spring Price List Senator variants.
The "new watches/revised prices" section of the 1961 Fall Price Lists gives more information on the variants of Senator available at this time. During this timeframe, this section of the price lists also shows the older internal Bulova model numbers and the newer internal Bulova model numbers used in the newer numbering system.
Subject watch could be a 1970 Senator, perhaps an early variant, which was continued to be produced and sold as Senator (unknown variant) up through 1970, however we don't have any ads for it that late. I don't see any ads calling this watch something other than Senator during this timeframe. Perhaps the ads were addressing newer models, but that doesn't mean older variants were not still being produced.
I'm still good with a tentative 1970 Senator unknown variant for subject watch.