Kz1000A gearbox sprocket

Hi people desperately need help , assembling the gearbox chain sprocket and not enough of the splines are showing to engage on the locking tab teeth looks like 6mm short !? , really need some help here because no way do I trust this without a securing tab that is locked 
so my thoughts have I got a kz1000A with kz900 output shaft or wrong drive sprocket , I don't know what to do , it's hardened steel I guess so won't machine that easy and I don't like the idea it's japanese so should fit perfect in 25 years of biking this is a first , I got the bike with bare output shaft so I cannot reverse engineer this headache 
ReSammie

Report spacer, sprocket, nut width.
 

Output shafts are the same for KZ1000 and KZ900.  Front sprockets are different.  Does your sprocket have a shoulder on the inside edge?  Maybe you should be using a flat sprocket.

The Kz900 and the '77 Kz1000, and early '78 model year Kz1000 have a different O.P shaft than the late model '78 Kz1000's and later Kz1000's. The late model O.P. shaft has the splines fit all the way through the counter sprocket. That O.P. shaft uses the nut with the shoulder  and the lock tab that has the spline pattern on the inner edge. The shorter Kz900 O.P. shaft where the splines do not reach the outer edge of the counter sprocket uses the regular looking nut with the locking tab that has the little nub that fits into the tiny hole on the counter sprocket. The counter sprocket nuts and locking tabs are not interchangeable. 

Here are both style counter sprocket nuts and the later style lock tab.
 

Better photo of the backside of the later style counter sprocket nut with with the shoulder.
 

The early style locking tab that is used with the non-shouldered nut on the shorter Kz900 O.P. shaft.
 

Thanks everyone this tap washer fits and do or some reason on tightening the sprocket went deep onto the splines I think the shaft came out a little further 
what a great community of people who love Zeds