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four speed gear blocks were quite common from the 1930's through the 1950's

one thing you might wish to verify before making any further changes is whether or not you have a drive train for 1/8" dentition or one for 3/32"

appreciate this may sound a bit odd but Italy did do five speed 1/8" drive trains at least as late as the early 1970's. Regina produced gear blocks for them. unsure if Everest/CAIMI did as well...

four speed gear blocks are readily available online

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