1990 shift shaft no longer available, upgrade to late model? Compatible?

[MeanGreenMachine]

So the shift shaft on my 1990 has badly worn splines, to where it might work if I tighten it down hard enough, but I don't want to have to split these cases again to change it if it doesn't...

Apparently, you can't get the OEM part (discontinued, not superseded by another part), but I read a post on here that mentioned that the 95+ shaft will fit, just that the splines are bigger and you need the matching lever for it. Can I upgrade to the newer part? I found a 2000 KX250 shaft and lever for cheap that the seller claims fits the KX500, and it looks like it does cross reference to the same year 500...

[motopunk]

you could compare the interchangeability of the 250 shift shaft to 500 engine here by the oem-parts lists..

www.cmsnl.com 

..absolute same parts have the same numbers. the shafts with bigger splining came in 94 to all kx 125-500 . but i dont think that the 250 shift shaft will match to the kx500 engine, theyre looking little bit diferent .

you could definetly use the 94- 2004 kx500 shift shaft with the right lever ,good used parts or they are still available new 

[sandblaster]

You can swap out the 94-04 kx500 p/n 13161-1203 shaft and lever into your 87-93 kx500 p/n 13161-1144 with no problem.
And you don't need to split your cases to change it out.

[MeanGreenMachine]

Man! You're right... I dunno how, but cross referenced the parts over and over and came to the questionable conclusion that the 00 KX250 part was the same... Oops. Also, after test assembling the (old) shift shaft/detent/drum, it looks like Kawasaki was indeed nice enough to put the majority of the moving/wearing parts under the clutch cover so you don't have to take the engine out of the bike to fix it... Thanks Kawi.

Anyways, I have a shift shaft out of a 2001 KX500 coming in... So I'll need a later year shifter lever too, right?

[sandblaster]

Yep