Ran with the gps today and the speedo was pretty close to dead-on going 65 on the speedo said 66 on the gps, same at 70, only one mph higher. The rpms were about 1800 at 65 and 2100 at 71 mph. Hard to believe that the speedo is so close to accurate. Perhaps the gears were changed previously but I didnt get that record.

96 T100 4x4 - 35's, 4" SL, 2" BL, 4.88s, ARBs, custom bumper & E9000 winch, etc.
99 F-350 4x4 superduty supercab turbodiesel longbed