Ineed, that is definitely a GK73. The frame and forks are a dead give-away, as they're completely different on the later models.
When you refer to the frame number, where are you reading that??

Stamped on the headstock. I used to do a load of consultancy work for insurance companies and have come across re-stamped frames quite a lot on cars and bikes. You can usually tell because of filing marks in the area or an unusually clean stamp on an otherwise tired frame or badly aligned numbers etc. I reckon it's the original number, but you guys are definately right about it being a 73a judging by the web link etc. The only other thing that occured to me was that it was made very close to the change over from 73's to 76's - maybe both models were being made together for a short time and some lazy sod forgot to change back to 73 stamp? A long shot but i've known it on cranes.

look again im sure it starts with gk73a

gsxr400 racer wrote:look again im sure it starts with gk73a

No its GK76a 104 then the last three identifying numbers.