I haven't had this one apart, as I don't possess a blade thin enough and there is no "tab" to pry on. I can't tell if the lugs are attached to the front or back portion of the case. Case back marked "10 K Gold Filled Bulova L6" with s/n on opposite end. Diamonds at 12, 3 and 9 positions
Per 1957 Linebook BAWDO131, this would appear to be a Beau Brummell "L", and a first for the database. Entry shows 2 variants, white gold w/black and yellow gold w/white face.
Mounted on a nice JB 10K plate mesh band and keeping perfect time.