the frame looks like the typical kalt 60 size,but the main rotor drive gear is not the correct one for any of the kalt 60 size. judging by the old style rotor head as well as that gear,i am guessing it is a 86 tooth,i would say that originally it was a baron 50 nitro. either that or it is a kalt gs alpha gasser with a older rotor head and different main rotor gear put on it.the gs alpha did not use the type of tranny style tail drive that yours has here. the tail ran off the top bevel /crown gear .yours of course doesn't have that bevel/crown gear