<VV> LM Differential Yoke end play question

[Charlie]

On an LM Differential where the yoke "clunk" in and out just a slight bit
(on both sides), can the end play be adjusted?

On page on page 4-10 (1965 GM Corvair Manual), in the exploded view "41" of
part 25, is the "side gear thrust washer" (part "41-C") a shim that is
replaceable with different "gauges" to clean up that end play? 

If replacing the "side gear thrust washer" will solve the end play problem,
where can these be had?

What is the correct thickness, to see if the ones I have are worn too thin?

I see no reference in the manual for replacing them, and it seems that this
is where the looseness is.

Any hints on how to tighten this up?

Thanks!
Charlie