Here is an interesting one from a garage sale. Bulova marked 10BRC Movement - rotor is stamped L1, case is stamped L6. I have had no luck researching this one, with the exception of finding one on Lisa's site listed as an unknown.
This one in my possession is backmarked "stainless steel back - shock resistant - anti-magnetic - self winding - *water proof * - Bulova" along with serial number and L6. Band is Speidel scissor center. Shadow face is marked "Bulova" and "Self Winding".