Ok, I did some more research at Kawasaki's website and Partzilla.
www.Kawasaki.com85 kx125 41034-1114
86 kdx200 41034-1146
87-88 kdx200 41034-1157
Partzilla.com
http://www.partzilla.com/parts/detail/kawasaki/KP-41034-1114.htmlThis Kawasaki 41034-1114 DRUM-ASSY,RR BRAKE is used on these models and components: 1985 KX125-D1 KX125
http://www.partzilla.com/parts/search/Kawasaki/Motorcycle/1986/KDX200-C1+KDX200/REAR+HUB/parts.htmlThis Kawasaki 41034-1146 DRUM-ASSY,RR BRAKE is used on these models and components: 1986 KDX200-C1 KDX200 REAR HUB
http://www.partzilla.com/parts/detail/kawasaki/KP-41034-1157.htmlThis Kawasaki 41034-1157 DRUM-ASSY,REAR BRAKE is used on these models and components:
1987 KDX200-C2 KDX200 REAR HUB
1988 KDX200-C3 KDX200 REAR HUB
So Kawasaki, Partzilla, and my physical measurements agree.
That being said, 86-88 kdx200 rear hubs have the same casting number embossed on them and the same physical measurements. Probably just a color change.
But, the 85 kx125 rear hub is different then the kdx200's .... but, I think there is a good chance that the 85 kx125 kx250 and kx500 may be the same.
Before you buy, simply ask the seller for measurements.