I took careful measurement of the new passenger axle from the outboard cv flange edge to the inboard edge of the groove with no spacer and compared that to the old axle from the outboard edge of the installed spacer to the inboard edge of the groove and they were within literally .0005" to.00075" of each other. So I slipped the new axle sans spacer into the diff and with some friction I was able to install the circlip snugly.
Unfortunately the driver side axles are different enough that with no spacer the new axle slids in and out at the diff with the circlip installed.
Since the spacers from each side are a different thickness and the driver side is thicker, I tried it with the pass side spacer but that is a c*hair too thick maybe .0005", so that while I could force the circlip into the groove opening, it would not seat down into it. I tapped it with a drift but with no effect. Even if I could drift it down, I would be concerned that it would be overtolerance too tight and likely damaged.
Ideally, I would get a thinner spacer so... the current spacer is .032" so I would think a .025" or so. I will try to get some info out of MB as far as what is available but I thought I would give the forum a shout anyway.Anybody got something kicking around in their toolbox or shop that might work?
Thanks for all the ideas; I'll get something worked out eventually

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1981 240D 143k 4 spd manual -SOLD

2004 VW Jetta TDI 5 speed 300k -still driven daily