Geerhed

I just bought a 1968 series 3 12 bolt rear end for my 68 RSSS Camaro .It was pulled from a 68 Nova SS. It was originally a BM 3.31 non posi. The gears have been replace with 3.73 and do not have gm markings. I am trying to identify the mfg. The only markings I see are a painted style stamp that says L45 does anyone know who may have made this set. The ring gear looks pretty beefy. Thanks everyone.