Speedo gearbox

Still working on my Mk3 rear wheel conversion, I was wandering if anyone has transformed the MK2 speedo gearbox into a MK3 one?? As the thing looks like openable maybe it is possible to save the $120 of a new one ?!
Philippe

Don't think that is possible. The MkIII drives from the left side while the drum brake models drive from the right. Therefore the drives are mirror images.
I did this conversion to my '73 850 Interstate. The only reason I did it was I had the parts laying around. A MkIII cradle was used with a small Airheart M/C from a flat tracker. The end result is good for amusement as I watch people check out the bike only to do a double take when they see the MkIII rear wheel and right side shift and primary.
Braking is only adequate and not noticeably better than the drum.
Ron L.