I may have found a ray of hope.
As Grigg mentioned, later model (1990's) topkicks had all electronic speedos and also were available with 2 speed axles.
From what I understand, There is a "buffer" of sorts that gets a signal from the hi-low switch and keeps the output to the speedo accurate.
I am looking for a part number or even a name for this component. All I have now is "VSSB" (buffer) module. I have had no luck searching for it on google. One place called something a "VSS corrector".
I really need to find a part name and part number for this. It really should not be this much effort.
