Well I guess this thread has digressed to random engine trivia, I guess my submission is okay... the original poster wants to learn about engines anyway.
The first year the low oil pressure 235 went into production was 1941, and only in the WW2 military trucks. Below is an image of a very similar 1942 235, notice the unique deep sump oil pan. Also notice the oil pan actually has "235" stamped on it.
[img]http://www.surfacezero.com/g503/data/3285/medium/IMG_19215.JPG[/img]