The blue switch does control the high speed fan, but what I have found to be different between the 6/8 is the 8 has a 3 speed fan and the resistance cut in/cut out points are different than the
6 , which is a 2 speed fan.
So the value of the resistor mod is different.
You can use resistors of choice [ I have tried many values ],
but the design of the system is for the aux. fans to be used as an aid under adverse conditions, not to be a continuously running part of the cooling system.
At the same token, I centainly see dropping the high temp cut-in down 5-7 degress a benefit to the running . But to use resistors of such value as to bring the fans on earlier than normal temps [which seems to be what everyone is looking for], is not neccessary . [ remember, the temp specs on your thermo are 'start to open' specs.]
I finally settled on a value that would bring the cut-in at a temp
that was reached when the car was at a few min. idle on a hot day. That seems to take care of any other load /heat conditions.

I would like to thanks Jim F for his assistance and his resistor
expertise. His design with the use of film resistors for heat/ohms
stability is very good.
Also, the low speed fan mod. that was mentioned is the bridging
of the a/c drier high side pessure sw. and that mod is simply a manual one with a cabin switch for the operator. This mod is
low speed fan .