When Was the SUA Model of The Four Wheel Drive Co. Manufactured?

Factual Questions
1

When Was the SUA Model of The Four Wheel Drive Co. Manufactured?

I am guessing 1920s to 1930s. Hopefully someone here knows?

Is SUA an abbreviation for something? The only abbreviation I can find which looks reasonable is Spring under Axle (automotive suspension design). When was that developed?

Thanks.

2

Dr. William Thomson’s observations were made in a 1901 edition of the Journal of Medicine where he stated:

" I have found my drives to improve my general health. The jolting which occurs when a motor car is driven at fair speed conduces to healthy agitation that acts on the liver. This aids the peristaltic movements of the bowels and promotes the performance of their functions"

However, spring suspension had been in use from the 1800’s and its not clear the “under axle” or “over axle” could be considered an invention of FWD previously BADGER . no one knows who switched around … it seems to be something you’d try and might do it one way for one model and the other for another, just to make it cheaper or something.