Screw back, no markings on outside of back, inside marked- stainless steel back-Bulova watch company-Swiss-51-86380-L1 0n movement, seems to need a mainspring, hour & minute hands pretty rusted, red sweep second hand, dial shows age{patina}. Case has been around the block too. Another clunker I got off ebay.
So L1 on inside case back and movement. Date is nailed down. Sure seems to match the ad Jay posted above. Has the stainless back, etc... Jay- what was the date of the ad? If ya remember. I didn't see the date in the graphic file name.
I'm good w/ Water Tight or Watertite....but would vote tentative.
In reply to So L1 on inside case back and by William Smith
That is from a 1951 ad here on myBulova. There are several ads out there for this watch. I have seen many of these over the years and have an example given to a friends relative by American Airlines in the early 50's as a million mile award. It is in the original box.
Jay
vintagebulova.com
In reply to 51 inside the case back, by bobbee
aha...it says 51 on inside case back. Picture was blurry, but I now see that's what OP stated in additional comments. I'm not familiar with Bulova stamping the date this way- 51 vs L1 (as on mvnt). Bobbee, just confirming- the inside case back of your example says 53 vs L3?