How much slip on a square shaft?

[UKMyers]

I have dual cases and just had a buddy build me a square shaft but he didn't cut it off to length. How much of the inner tube should I have showing for it to work properly? I'm running it on a SASed 94 Runner with 4" springs and dual cases. Thanks!

[Hyena]

allow for about 4-5 inches of inward travel of the shaft.  make it as long as possible though.

[UKMyers]

The length of the outer shaft is just about the exact length from flange to flange. I'll just hack 5" off it and call it good.