interchange on that box is in fact '62-'72 a- and b-body. Starting in '65 there are two varieties; the 6-cylinder cars got a box with plain bushings and the v8 cars got a lower-friction box with ball bearings to maintain steering effort levels despite the heavier engine. The difference between the two is not so large that one would readily notice it; if you have the option of two boxes in equally good condition then sure, pick the ball-bearing one, but if you have to choose a nice bushing box vs. A worn-out bearing box, get the bushing box. Look for a box that has at least a couple of threads showing on the sector shaft adjustment screw at the top of the box, and no discernible lash/play when you rotate the input shaft back and forth.
If you strike out locally i have a nice bearing-type box in good shape out of a '70 dart; send me a pm.
