That in and of itself is a PITA when trying to get mounting bolts started when you lift the new gear box to the frame.
Removal of the pitman arm with a puller is needed. Removal of the fluid lines with line wrench crowsfeet or wrenches. Unbolt from frame and completely clean the frame and inspect for cracks.
Reverse to install and then fill/bleed the fluid. DO NOT fill fluid and start engine and turn left and right with the front tires on the ground. You should elevate the tires and as you top off fluid as needed, turn the tires left and right, off the ground, slowly to purge the air from the system. When you have done that and see that the fluid is remaining full, then you can start engine and again turn slowly and watch fluid level. THEN you can put tires on ground and do the same again with the turning and watching fluid level. Then roadtest and top off fluid as needed. Use power steering fluid called for in the manual.