Classic Auto Air - 1973 Duster - Fan switch help

So I purchased the Classic auto air Classic Auto Air 20-286 Plymouth 1967-1974 Non Factory Air kit. however the instruction are only for up to the 1972 year. The dash in mine looks like this:
upload_2020-6-29_13-31-21.png

but the switch is supposed to be separate
upload_2020-6-29_13-32-22.png

Does anyone know how I would rewire the harness? It looks like they are providing a switch to replace the original one with int he dash? upload_2020-6-29_13-36-53.png

upload_2020-6-29_13-38-7.png
Wiring from their instructions above.
Wiring diagram from 1973 Wiring book
upload_2020-6-29_13-39-32.png

Can anyone assist with this? Need to know high, med, low and which one not to use, as the 1972 had a 4 way switch? or one more than the 73?

Thanks for all the help I can get.

Scott