a500 ?

Can you tell me what year the overdrive planetary setup pitch changed from 22.5 degree ..to 15 degree ? Also is this the same for both the A500 and the A518 ? thanks . If I go looking for an A500, might as well find the updated version.
A500 and A518 use the same planetary setup. Everything comes in a kit. OD sun gear, OD planetary, and OD Annulus(ring) gear. My catalog shows the late design happened in 1996.