This gearcase can fit the "worktwins" 6, 9 , 12 built in 1979-1984.
The last two was a sort of "frankiemotor" using the 9.9-15 powerhead, the old QD 10 lower and the MQ 9.5 gearcase
The 14 is a "second generation" workhorse that used the bigger gearcase of 25 hp and a custom lower unit.