Gas Cap or Radiator Cap for a Ford Model A? 2-3/4" OD in front and 2-9/16" OD in the back. Double flange driveshaft joint. Marked S-3 with "DRH" below it. Has Neapco ujoints. Measures 8-3/8" inches long. smaller 3-1/2" OD flange has 4 hole by 2-3/4" bolt pattern, Larger flange is 4-1/4" OD with four hole 2-7/8" X 1-11/16" bolt pattern