No, that is incorrect. We have an article on our site on how to install the 80's Monte Carlo SS quick steering box in the GS models. You can use the box from the S-10. I believe I have the info listed on our site for all the cars that have manual boxes and interchage.
Thanks George. I am kicking myself for getting rid of the manual box that was on my convertible when I swapped to a power setup.
Chris I have a manual steering set up off of my 72 GS if it would work. $40.00 plus shipping if you are interested. i am in nebraska. evening ph. 402 463 1669 thanks john n