Help getting mainshaft nut off!

[McBrain283]

The strip down of my 1952 80" gearbox has been going quite well. Transfer case, output housing, etc all done with no issues.

The castellated nut on the front end of the mainshaft (within the bell housing) is causing me some problems

Gearbox is locked in 2nd + 4th gear
Locking tabs have been flattened
I know it's a left hand thread

So I started by using a punch on the shoulder of the castellations but it's not ideal. Is there any risk of damaging the gears within the box doing it this way?

Last night I made a special tool but this has also not been successful. I could probably get a bit more torque on it so the next option is to try more leverage.

I have tried heating the nut, but only gently. There is an option to use a bit more heat.

So I'm looking for any tips here. Go harder withe the torque and heat? Use the punch for impact? Or perhaps I go ahead and remove the bell housing with the nut in place. I could then press out the shaft with the bearing and nut attached and do it on the bench. The problem here is that the bell housing is too big to fit in the press.

[McBrain283]

Photo of nut for reference

[McBrain283]

Ok, I popped into the workshop before work and tried giving it another tap with the drift. I hardly hit it am it's off!!

Not sure if it sitting overnight in penetrating oil helped. I reckon I just needed to spend time writing a forum post to get Murphy's Law working for me....

[roverrescue]

Story aligns nicely with my hard earnt knowledge about projects.

That the most efficient and productive work happens some point after the swearing stops and before the third beer ….

S