As many know the Tubo Jet unit was used by many boat manufacturers. I'm in need of the coupler (OMC 340871) preferably used are a better price than the dealers want. Turbo jet marine has the same price as the dealer. Basicly the damn thing is an aluminum 3" round and tall threaded at both ends cup with rubber inside to dampen the pulses from the engine. I believe that this may be an aftermarket part (not manufactured by either OMC or Turbojet) the couple mounts on the shaft of the jet gearbox, and then a stub shaft that is splined mounts in the top. This stub shaft of course fits into the crank, and would be different for each powerhead mounted on the gearbox. Any info greatly appreciated. I'll engineer and machine something new before I pay big bucks for this thing 
Dirk
Dirk