Steering box question

You'll need a 1&5/16 socket to move the 71 arm to the 74 box. Some do use a splitter/pickle fork but there is a proper pitman arm puller for this task. No risk of damaging the gearbox internally with the proper tool.
Chrysler had issues with the 3 bolts, steering gear to K member, working loose. They provided major funding for development of the thread locker we now know as Duponts Loctite for this one issue and application.
I think their whole problem was welding the nuts distorted the land steering gear sits on. The land on the gearbox was always milled flat. Anyway... check clean mating surfaces, evenly torque the 3 bolts. If you happen to have their special interference thread bolts, a 12 point socket fits that head. 7/16 or 1/2? I forget.