My '21 Touring has been updated sometime in the past 95 years, actually 96 come May, with a starter , battery , and generator. I replaced the metal part of the coil box with one that doesn't have the original switch on the box, since my car now has the switch on the dash. I reused the original wood parts of the coil box with the newer metal part. On the wiring diagrams that I can find for 1919-1925 Ts the wire from the ignition switch COIL terminal to the coil box is attached to the lower terminal on the box on the drivers side. My lower terminal is on the passenger side. I know that the grooves in the wood parts of the box are on both sides and the inside wire would connect with the brass strip in the bottom of the box. I'm guessing that it makes no difference which side the connection is installed in, right? Why is there a hole in both sides of the firewall and grooves in both sides of the coil box? Other years connect to the other side? Being a non-starter car make the difference? Some wood-firewall cars have terminals on both , driver and passenger side? Thanks
All Model Ts and TTs prior to the 1924 model year's high firewall had ten holes in the firewall for the ten porcelains on the coil box: four for the sparkplugs, four for the timer, and two for each power source; the magneto and a battery. The left power was magneto and the right was battery.
Now, if a car was equipped with the starter, generator, and battery it would have a coil box Without the front mounted ignition switch and that box would have only nine porcelains. That power connection would be on the left side for the wire from the ignition switch on the dashboard.
I hope that this helps. Bill