Never really understood why there is a threaded plate on the bottom of the radiator mounting assembly ... instead of just a bolt or a castle nut with a washer and cotter pin. Any technical reason for that plate?
The plate is so that when you go to take the nut off of the top end of the stud that secures the bottom of the radiator, the stud will not turn. You cannot easily get to the stud to hold it, nor can you easily get to a NUT at the bottom if the stud to hold it from turning. With the plate at the bottom, you don't have to hold anything as the plate strikes the frame channel but an nut there would just turn.
There are two styles of this nut (plate), long and short. The short ones will, and do turn when trying to turn the upper castle nut. In '25 or possibly '26 Ford finally made the nut (plate) longer so it would not turn when adjusting the top castle nut. It strikes the frame rail, and prevents the stud from turning.
Thank you Larry for your better and more complete explanation,....I should have mentioned the fact that there are two different sized plates. I have used both, and as you say, the smaller one does not prevent the stud from turning when you try to loosen the top castle nut. For this reason, I now, always, use the larger plate, because even tho' it was designed for use on the "new improved" '26 - '27 Model T's, the larger plate does exactly what it was designed for, and the smaller plate does not. Even though it's wrong, both of my '23's have the larger plate, because it works so much better. Obviously, there are many reasons why the "26 - '27 was called "the new improved" Model "T", this larger plate that is hidden inside the frame channel in one more little "improvement because it ACTUALLY DOES prevent the stud from turning when you loosen the top castle nut, and the smaller plate which was used on the earlier "T's does not,....shhhh,......don't tell anybody,......harold ( ; ^ )