Rebuilding a 489 rear

[toppsauto]

I changed the ring & pinion on my 489 case. There is a washer between the outer bearing and the yoke on the coarse splined but does not fit on my new fine spline yoke. Does anyone know what is the purpose of this washer? Or do I does it belong there? At first I thought an oil slinger, but it's too narrow for that. I'm thinking someone put it there to save the old crush sleeve. Thanks in advance

 

[Yatzee]

I've done 489's before and I can honestly say that you had best have about 6 hours to get the
gear settings right. Mine did not use a crush sleeve, rather shims, but there's no mistaking were
they go so if this is a shim washer you got it in the wrong spot. If the washer is the one that
goes under the bolt head that holds the yolk that's another issue. I recommend you purchase
a solid spacer not a crush sleeve and get a shim pac for your pinion gear. Rebuild parts diagrams
and setup procedures can be found all over the web.

 

[toppsauto]

I found a service diagram which shows the washer in question, between the yoke and outer pinion bearing. I circled it in the attached breakdown. It appears it is used only on the 489 case not the 742. Its purpose is a mystery.