Hi Dave,
It's always been held to the shaft with the original roll pin. It's actually much easier to strip and work on the gearbox after it's been modified. Getting the selector off the shaft and the H gate out is a real bugger before the mod. You don't even need to pull the extension housing after it's modified.
Not long now and you'll be able to sit in your car and make broom broom noises.
Bernie,
I was contemplating popping down last Saturday but I was flat out finishing the gearbox. Sounds like you are making good progress. I'll have to come for a look.
Cheers