I ended up getting an swiftamatic so I can make my 5220 into a duel range diff and have a few questions. I also have never even used one so this is a learn as I go situation.
I started pulling the donor tranny apart and noticed that the Shifter pin sort of slides in and out but does not seem to engage the gear - now the rod that would run to the dash is not hooked up so I am not sure if that is part of the problem or not. It looks like everything is in excellent condition inside with little wear. It seems the shifting yoke moves freely but is it supposed to turn freely on the clutch sliding pin (as it is not pinned to it so it can not "swing".)

The other question I have relates to the way to measure the end play? From what I read (and think I understand) I believe I remove the diff as a unit and just slide it into my 5220. (was not going to take the diff itself apart - don't see a need unless I am missing something) Then the only measurement I need to be concerned with is the end play? Maybe?
Now to question #2: I looked at the swiftamatic service book in the install section it says to make sure the diff is centered by using the shims that fit between the axle housing - is this the end play? If so how so I measure it with accuracy? I have calipers, feeler gauge, and such but just am unclear where I take the measurements at?
Sorry for all the questions but this is the first time I ever messed with something like this and am a little unclear on things. Seems like a very straight forward swap and one that I should be able to easily do but I am very concerned I am missing something and want my measurements to be correct.
Thanks, this is my Monday holiday project so I am looking for help from everywhere and anywhere.