Changing a 67 Camaro from manual steering to power steering.

My question: is the big nut that holds the pitman arm onto the power
steering gear box the same size as the nut holding the pitman arm onto
a manual steering gear box?

The nut from the manual gear box feels like it wants to start onto the
power steering gear box but then stops and I do not want to force it
on and strip threads.

Any input appreciated.

Thanks!