[gmc684x4]

You can swap spindles 67-70 or 71-71 or 73-87 set
Use stock a arms and cross member need to use matching ball joints and steering linkage

If everything is old and worn i would go for the 73 up style as new parts are cheaper then a two year 71-72 setup and bigger then the 67 70 set

Steering box will bolt in if you have the 4 mounting spots on your frame

If your frame has 3 mounting holes there are several threads on this site how to create a recess in the frame to accommodate the power steering box

What style of acc belts ars you using ? Some of the aftermarket ps pump kits do not fit out of the box as advertised