I can only recall one harness in the kit I used that adapted the existting wiring in my non gage console to the required wiring in the console to accept the gages.
If I read Rick's on line catalog correctly, page 199, top right states the following:
CONSOLE GAUGE CONVERSION HARNESS
Install the console gauge option just like the factory did in non-gauge cars. 100%
correct wiring, colors and connectors. Complete kit with detailed instructions.
Use Console Harness below to complete installation.
6706 67 A/T original console shift ..........
6709 67 A/T original column shift ..........
6705 67 All manual trans .......................
6806 68 A/T original console shift ..........
6809 68 A/T original column shift ..........
6805 68 All manual trans .......................
6906 69 A/T original console shift ..........
6909 69 A/T original column shift ..........
6905 69 All manual trans .......................
I believe that you only need to select one harness from the above listing that fits the particulars of your car, i.e. manual vs. automatic, original column or console shift, etc., and that the one, correct harness will adapt your current setup to accept gages.
There are two othe console harnesses listed below these in Rick's catalog. As I would read the catalog, these would be replacement harnesses for cars that either came with gages or for non gage cars. To me these listings are just to simply replace what you already have without converting over from non gage to a gage setup. Best bet would be to double check with Rick's.
Richard