A question for the tranny builders...........

I need to fix or replace the 5-speed tran in my 88 Montero. It's got a broken gear. I bought another trans from a salvage yard, same one, but the front shaft (input) has side-to-side play. I haven't measured it yet, but it seems like maybe 1/8" total. Any idea how much play is okay? The old tran has a much smaller amount of play.
Thanks for any advice.