As Tim said, the Sting Ray guitars are from the original MusicMan company before EB bought them. I don't believe they have any records from that era.
Many years ago a read both Forrest White's book and George Fullerton's first book, and can piece a bit of history togther from these sources. Music Man was owned by Forrest White, Tom Walker and Leo Fender - although Fender's participation was kept secret until 1974 or 1975, whenever his non-compete agreement with CBS expired. Leo Fender also owned a company called CLF Research in addition to being a partner in Music Man.
Per an agreement, Music Man built and owned the Music Man amp factory, but Fender's other company, CLF Research in Fullerton, CA, designed and built the basses and guitars. At some point circa 1979, Fender had a falling out with the other partners and sold back his shares in Music Man, but he kept the contract to produce the guitars and basses. Fender organized G&L Guitars and produced both lines in the same factory in Fullerton for about a year (1980?). There were some issues with the Music Man models, so Music Man terminated the contract with CLF Research. At that point the Fullerton factory switched over to only producing G&L Guitars and Leo mothballed the CLF Research name.
The Sting Ray guitar has a lot in common with the early F-100 G&L guitar; some of the Leo-era G&L fans also have info on the Leo-era Music Mans - there is a link on the Guitars by Leo forum to a site with info put together by one of their members who also writes for either Vintage Guitar or 20th Century Guitar (one of the two).