Mystery Bike

The other day I was given the opportunity to buy what I was told was a 1980 SR500. Its in pieces and the sticker is almost completely worm off. The numbers are still on the frame but I haven't been able to find anything on it anywhere. Hoping you guys can give a bit more insight on what I've gotten myself into. The numbers are 2J2-000393. All I've gotten so far is its a 78-81 SR500 based on the 2J2 but it could be an F or an H and this 9 digit vin is driving me bonkers. 1st time bike owner/builder with no clue what I should expet.

 

If the 2j2 model ID code was used for all 4 years, then the 6-digit "serial number' range would be incremented each year (to prevent duplicate or almost-duplicate full VIN's). Give that the serial number is 000393, I would think that it's a 1978 model, as the lowest s/n range occurs in the first year (i.e. 000000 -thru 0010000, or, more likely, since Yamaha typically (but not always!) starts their s/n range for the 1st year of production at bike # 000100, the bike #000393 is the 293rd one built in the 1978 model year).