Creepy

(Pardon my non technical English.. at least I try...

Last Sunday I broke my 5 speeder.
It's a Classic Turbo with 330 bhp/440 Nm and a WRX 01 5-speed gearbox.

When driving normally, I was in 3rd gear, when I accelerate out of a corner and suddenly... BANG...

Result : main shaft snapped in half, between 2nd and 3rd gear ?

WTF ?

I still could use 1 - 2 and reverse, but 3-4-5 were gone.
Today I dismantled the gearbox and found the snapped shaft.
By my knowledge, is this not common, so I want some info on how this could have occured...

Thanks...

2ndgear

sounds like the 3rd and 4th fork has snapped (common) and wont alow across the gate and forward into 5th. I have seen this before