Stake Nut size for output shaft?

Hey guys,

Alright so my transfer case is leaking from where the front drive shaft enters the case. I'm guessing it's a seal which it most likely is. The steelership wants 290 for the work, so I am going to do it myself. Just a quick question, Does anyone know the size of the stake nut on the shaft? I searched and found 30mm and 24mm, My problem is I am a student so I am doing the work in the driveway and have a socket set but don't have them sizes and was wondering if anyone knows the exact size for that nut? So I can go get the socket before I take the truck apart...

This is probably way longer then it has to be...

 

http://www.yotatech.com/f2/driveshaft-center-bearing-flange-nut-62576/http://www.yotatech.com/f116/wow-transfercase-flange-nut-227923/

 

Awesome thanks, I been finding a lot of 30mm, but a few 24mm came up so I was just worried.