I have had both rotary and rack - I prefer the rotary. Not that it matters, they both are tried true and mature. They each use different cables, I have never had to buy a cable for a rack system.
You should be able to just reach under and feel the difference. Rack has a 1 inch square tube, about a foot long going across under the dash with the steering wheel input gear in the middle. A rotary has a 7 or 8 inch round gear box. Hard to mistake the two.
From the standpoint of testing, just pulling the pins at the back and freeing the cable will let you test just the cable. You can both feel how free the wheel turns from the front and you can push and pull the cable end to see if there is slack in the back. The back end is identical on either type of system. Common to find old dried up grease that is preventing free movement. Clean it up and lube it fresh and see if that fixes it.
Rick
