2 - Globe Drivesaver #504 Vibration Reducing Transmission couplings.  These are New Open box parts $500.00 for the pair.  Free shipping USPS within Continental Unites States.   

Globe Drivesaver coupling
4 bolt pattern with 4 1/4 in. bolt circle
7/16 in. bolt diameter
2 1/2 in. pilot diameter
5 in. flange diameter
6 in. coupling diameter
1 in. coupling thickness
675 ft. lbs. maximum torque rating
Manufactured from a stiff yet resilient elastomer that withstands salt water, oil, and gasoline
Installs between transmission/v-drive and propeller shaft couplings isolating the propeller shaft from the boats engine and transmission   
Reduces damaging corrosion to the vessel by blocking electrical currents in the water
Absorbs vibration and reduces noise in the driveline
Minimizes impact damage to the engine and transmission by creating a weak link in the driveline
Fits Volvo Penta MS3 and MS4 model transmissions
Fits ZF IRM41A2, 41A3, 50A3, 50A4, V2 and V3 model transmissions
Fits ZF Hurth HBW 360, 360A, 450 and 630 model transmissions
Fits ZF Hurth HSW 450A, 630, 630A, 45A, 63 and 63A model transmissions
Fits Borg Warner Velvet Drive model transmissions with 5 in. flange
Not recommended for v-drive applications where propeller shaft passes through transmission