pitman arm question.

[long69]

gathering up parts necessary for a conversion to power steering. my question is the pitman arm. i understand that you will need a new one on the power gear box. is it because the one off the manual box wont fit onto a power box or is it that it requires a completely different one (size wise). i ask because the power box i got has the arm already and it looks to be exactly the same as whats on the truck now. new (used) power steering gear box is a later quick ratio from late seventies.

thankx