Split Coupler | Flange Diameter: 5″ | Overall Length: 3-7/16″ | Shaft Diameter: 1-1/2″ Transmission: BorgWarner, Hurth, Newage. Number of Bolts: 4. Bolt Size: 7/16″. Bolt Circle: 4-1/4″. Pilot: M. Hydrasearch manufactures a full line of transmission couplers for most marine transmissions. Our couplers are cast from ductile iron and machined to SAE J755 specifications. Most of our couplers are machined with our universal bolt hole pattern. Supplied with mounting hardware.