at a guess it could be a SG....
could be a super goose but it does not have the original tange forks from the era ..... one way to tell is the SG had a full cromoly frame whereas the standard goose had only a cro mo and a steel triangle.... i just cant remember if the cro mo was the front or rear triangle...either way..she was made in the USA..soda blast & chrome her up stick some early super goose stickers on her and only a fickler like me will ever spot it... nice ride... original seatpost,bars,headset,rims and brakes.(but not the levers but you maybe lucky enough to get some NOS off ebay..)... oh I just remembered.. if she has the MX cranks then she is a Supergoose for sure....just a little suspect on those forks though...nice score bro... I have one in my shed still shiny as she should be...orginal stickers and all...
does the seatpost clamp have any engraving...some said mongoose... some said supergoose... but that is obviously the original anodised alloy job which to me points to the legendary SG