'64 Valiant Steering box

The power box has fewer turns lock to lock( about 16:1) than the standard 24:1 manual box. The power box is pretty much the same unit from '62-72 on the A, B, and E,bodies. There are some appearance differences and the return line and pressure line fittings are sometimes different, but, they should swap over. Changing over the whole valve would require you to re-center it for proper operation. That's a delicate procedure, and if you're not careful, that can be a messy job! The '64-up C-body and the '73 and later Mopars used the large pitman shaft. If those mounting bolts were loose for some time, you may want to check the ear holes in the box to see if they got too egg-shaped, resulting in a thin edge that might break.