Willy,
Chevrolet started naming their car series in 1923 and continued until 1933. The names are as follows;
1923-26 Superior
1927 Capitol
1928 National
1929 International
1930 Universal
1931 Independence
1932 Confederate
1933 Eagle (Master), Mercury (Standard)
Trucks were not included in the car name series, they were just identified by their letter series like LQ or LS etc.
I agree, you have a 1931. The extra long running boards make me think your truck was originally a single wheel truck with rear fenders on a body of some sort, the dual wheel trucks had short running boards.
Mike B
