The serials for early mm stingrays are all over the place... I've tried to date mine and went to the mm 'guru' site.. http://www.musicmanbass.org/
"Unfortunately, and as incredible as it may seem, records for Pre-EB instruments were never made. My website is to give a general idea of age of an instrument. To accurately date your Bass, the neck would have to be removed to observe the date stamps on both the neck heel and in the body pocket. This can be done by a luthier for a small fee. Other than that, the only advice I can give is to do a comparison with other serial numbers on my website list. But, as you can see, by comparing your serial with others on the list your Bass can have been made in either 1977 or 1978. In addition to not keeping a data base, Music Man made no attempt to keep serial numbers in strict chronological order. As neck plates (with engraved serial numbers) became low on the process line, the containers were merely topped up. As a result, earlier Basses could end up with a serial indicating a latter year."
I'm sick of dismantling my basses for the sake of date accuracy. The serial on mine is on the neck plate (three hole, tilt).
Post a piccy of your bass please.