if the shims are in decent shape when dis assembled, I've never had an issue with re-using them as long as they weren't "messed" up taking them apart.
I also have a bin with shims I've never used thru the years, just in case.
maybe I'm confused reading the first post
you say you took it apart with lots of shims, 2.5
your new measurement is 2.4
maybe that is how this axle is setup???