There was a guy on here selling 2 speed jackshafts for like $80 shipped, and BMI has the dual clutches for around $50.:hammer:
But good luck on finding the mounting bracket. You may have to get the dimensions and have one made, For some reason they are always missing, because the old 2 speeds had some kind of a spring that always used to break , and then the 2 speed wouldn't work. So then people would pull them off and try to use just a regular clutch and they usually lost the jackshaft. I have 2 Boonies now , and I went to a TAV backplate on one of them which has the jackshaft built in, Then you can reverse the wheel , and you are good to go. Or just buy a TAV.