Trully a unique opportunity. This is a one of a kind gearbox. It was custom built by the factory for Dr. John Wittner's AMA Race Bike. It's a C.R. A Z=17(close ratio "type A") gearbox with a 17 tooth primary gear. It is built from all new parts and has never been used. In it's current form, it is for use with an exposed driveshaft MG that takes a five speed. The rear cover can be changed for any MG that a five speed can be fitted to and can then be used with enclosed driveshaft type swingarms. The charge for the cover swap, plus adjusting the shimming to suit the new cover is $240. If you also want to keep the original black cover that will cost an additional $100 or $340 total charge.
This is the racing close ratio developed in the seventies. It is by far superior to the LM IV or the close ratio used in the Daytona and 1100 Sport. It would be an excellent update to one of these bikes.
The vast majority of close ratio gearboxes were built by racers who bought close ratio kits which required a donor street (helical gear) gearbox. Some racers were qualified to build these special gearboxes. Most were not. This is probably the only factory built close ratio gearbox available anywhere in new, unused condition.