1963 Bulova Accutron '400'
I picked this watch up several years ago from the original owners, along with the 430 model; his and hers set. Recently uncovered an ad for the 400 variant and based on ad and case number matching the pricelist and crystal specs, I feel confident calling it the 400. Case and back are 10K gold filled, dated M3, case # is 2387; dial looks to show some patina, but may originally have been a gilt color, uses the USA-made 214 movement dated M3; came with the display box and original band and accessories.
Ad is dated 1965. Accutron crystal specs state case 2387 associated with several variants, one of which is the '400'. Pricelist has this variant at $150. Ad shows the '400' at that $150 price and visually matches watch.