74 f-250 shouldn't have a D-80 in it. get me the bom number off the axle tube itself, along the axle tube looking at the cover about 2/3" off the center section will be a 610XXX-X number stamped into the axle tube.
But it sounds most definitely like a D-60, if it's for a car or jeep the 3" axles are all you want
1995 Jeep gc ltd, 2005 Jeep gc ltd , 71 Dart, 73 RR 440-6pk, 78 Mag GT, 85 Power Ram W-350, 92 Daytona, 99 Dakota, 08 Ram 2500
Less than 8 is like playing with half a deck
Long Island Motorsports Association