I'm guessing he's talking about the pitman arm, aka the big cast-iron lever that connects the whole linkage to the steering box? If so then yes you can use the D50 one, no it's not the same as the D60 one and thus your wheels won't be able to turn quite as sharp, but still it will connect to both the steering box and the draglink in a safe and secure manner. Same holds truth for 2wd pitman arms as well, really as long as it came from a '80-'96 truck (or van) you can use any pitman arm, just your max steering angle will vary from one to another.