4-2-669 Flange Yoke 1550 Series , Pilot: 3.750 , Bolt Circle Dia: 4.750 , Holes: 4x 0.512 Centerline to Face: 2″ Rec Pattern

4-2-669 -- 1550 Series Flange Yoke, 4-Hole, 4.750" Bolt Circle

The 1550 series sits above 1480 in the Spicer/Dana strength hierarchy -- the 1.375" cap diameter is shared with 1480, but the wider trunnion span and heavier ear construction of 1550 provide higher static and fatigue torque ratings. This flange yoke's 3.750" pilot is 0.250" larger than the 1480 equivalent (3-2-489), making them non-interchangeable at the companion flange. Always verify pilot diameter when sourcing replacement hardware for heavy-duty axle applications.

The 2.000" C/joint-to-flat dimension affects the total assembled driveshaft length -- longer than the 1480 equivalent's 1.500". When converting from a 1480 to 1550 series shaft on a truck with an existing companion flange, the extra 0.500" in offset must be accounted for in the overall shaft length calculation. The 0.512" bolt holes are slightly oversize versus the 0.500" bolts used on 1480 -- confirm the fastener OD clears cleanly before final torque.

Pair with a matched 1550 series U-joint and a 1550-rated weld yoke at the tube end. The companion flange at the differential must have a 3.750" male pilot to register correctly with this yoke.