In 1966 I ran in the Orange Bowl 9 Hour race. The single engine class we were in was won by a European built v-bottom boat with a 90ci OMC.
This motor was equipped with a "speedmaster" style lower unit. There was a spare unit secured in a cradle in the boat as well. does anyone know what kind of lower units these might have been. I am not sure but this crew may have changed that unit during this race.