Gen1 and Gen2 are the same except,
The Gen1 has the center stand mount and the Gen2 does not.
The Gen2 has 4 small holes in the frame for fairing push-pins to fit into, that the Gen1 does not.
Otherwise, they are the same.
The Gen3 supposedly uses the same frame as well(no center stand mount), but I have no personal experience with it to say if there are any variences in the Gen3 frame or not.