Oh my goodness! you just posted the exact thing that you said wouldn't work!
That states that a 6 volt coil at 1.5 Ohms works with an external resister of 1.5 Ohms in a 12 volt system just fine.
It also states that the newer designed coil works better. Something that no one here has a problem with. At least I don't, because that's what I replaced my 6 volt coil with when it finally died.
BTW Tony, concerning my 1964 Ford 4000. I found the boxes from the last 3 coils I got. The 6 Volt coil was on it and died. More than likely in the late 1990's. I remember raking hay and it just died. Was it the original coil, no idea, I just know it was the coil on it when I had it converted from 6 to 12 volts in 1986. Local AG teacher at Tech school did it when tractor was in for a rebuild. Cam shaft gear blew up. He added a Ballast Resistor to the wiring, put a Delco 10SI on it. I could finally put some lights on the 4000!
I went to the local Ford dealer, they sold me this:
CNH Original parts E8TF12029BA Made in Mexico - Didn't last long, going thru field with a rear scoop full of dirt and it just died. Lasted maybe 5 Years.
Lets say early 2000's. It was replaced by:
TISCO 290317 replaces Ford D5TE12029AB Made in USA
OEM applications
FORD TRACTORS
2000-3000-4000-5000 1965/UP
2600-3600-4600-5600-6600 1975/UP
12-VOLT
GEEEEEEE that says all the X000's from 65 up!
That coil still works, but I was chasing a short in the system and did an upgrade to all Blue Streak products.
Current coil:
Standard Blue Streak FD471
Made in Mexico.
Tony, you can have all those fancy tech documents and diagnostic tools, but when I am out in a field with hay down, I just need the tractor to RUN.
I think that was all any of us wanted, a Tractor that runs. We are not working on hot rods.
BTW, I can see that the wiring on the 1974 2000 I have is original. You can tell because the cloth over old wire with original ends on the wire.
I got it in 2023 after my cousin died. He was the second owner.
Have a GREAT day!