According to the master parts book, a CC303 is a 1942 model @ 160 WB. However, parts books are not always correct. Apparently you have what you have. A 270 is not listed to be offered in a 303, but it could have been a government or emergency vehicle that was specced with a 270. You probably have the 1350 2 speed. It would probably be 5.83/8.10 or it could possibly be 5.14/7.19 which would be a good ratio. It is hard to tell because the truck you have does not conform to the master parts book.