I have a '20 Model T Coupe with non-demountable wheel. I also has a starter and generator.
Does that mean, the engine has been replaced?
Richard
No, they were available in 1920.
If the engine is the original then it could mean, the starter and generator were added after the car was bought or the wheels were replaced at one time. By 1920 all cars were equipped with starter type hogs head and if the car did not have the generator bracket then one could be easily attached along with a new timing cover plate. For a while the none starter equipped 1919 into maybe 1920 used the non generator front plate and a casting where the generator bracket went that looked like the old style bock boss for the timing gear. They would have come from the factory with block off plates.
Non-demountables were still standard on the open cars in 1920, and for some years after that. It's quite possible that somebody could have ordered them on a coupe to save money.
What did they do for a spare? It has the spare tire rack, but it wouldn't be of any good for a non-demounntable wheel.
From the encyclopedia:
http://www.mtfca.com/encyclo/1917-20H.htm
"The Ford of 1920 continued in the style of the 1919. Electrical equipment and demountable wheels were standard on all closed cars, and optional on the open models. Trucks apparently were not given the starter option until 1921."
Apparently somebody has changed out the wheels on your car sometime during the last 92 years. The engine may also have been changed, but whatever engine was there in 1920 had a starter and generator too