I think it's .008-.012 end play on the axles (somebody will say if I'm wrong). You can measure with a magnet dial indicator. Honestly, I haven't measured one since my 20's, I just always went by feel (it's why I say "I think" LOL). Pull the axle in and out, you'll hear the "clunk" of end play, but the movement should almost be unnoticeable to feel or see. If in doubt, use a cheap indicator