Thank you for your advice! I do not remember how I chose 20 amps for the main feed, but I do agree with you that I do not want to put a bigger one in without knowing that to be the problem. When I took my first test drive I got near 45 minutes of use with no problem other than me learning how to drive it, so it seems like everything was correct at that time.

When I tried the kick down feature it did not work 3 times. It did work on the 4th try, but the overdrive stopped working at that time. Since then it pops the fuse immediately upon activating the solenoid.

I use a plain jumper wire to test the solenoid. It seems to be okay with that. It works without smoking. The fuse pops when I ground the governor. Something is wrong there. I do not know what to think of the relay test not giving the result described in the Ford manual. I have not yet figured out what to check on the kickdown switch.

I am confident of the solenoid being 12V based on my checks working and presumably having been in use by the previous owner.

Again, thanks!

1950 GMC 100 Panel Truck, 1958 270,
3-spd Saginaw with BW OD,
3.73 12 Bolt Differential from a 1966 C10,
Front Disc Brakes
Bought it in pieces 9-1976, driving since 6-1978
Follow in the DITY