The 6V starter has a mount hole spacing of 2-1/4″ and a 12V starter has mount hole spacing of 2-1/2″. The 1956 bracket has only 2-1/4″ mount hole spacing, whereas the 1957 bracket has 2 sets of mount holes so you can use either a 6V or 12V starter. You can’t bolt a 12V starter to the 1956 bracket. See pic of 1957 bracket 376885.
Bob
1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1955 Johnson QD-16
1957 Evinrude Fastwin 18
1957 Evinrude 3022
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20
1982 Evinrude 25hp
“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."