The tire size is P205/70R14/93s, The tires are Radial G/T Road Huggers. Thanks for any info you guys can give me. Is the speedo gear in the tranny and how difficult is it to change out?
Try a 40 tooth speedometer gear for the tire/gear combination you listed. My experience has been 1 tooth per 3 mph of speedo reading change. It is not a difficult swap. Before you start, however, make sure that everything around the speedometer cable going into the transmission is spotless. It would wreck your weekend if a piece of debris were to find its way into the transmission. Recommend raising the driver side higher than the pax side. There may be a little tranny fluid spill, so be prepared.
IMO The absurd reading seems to be more of a speedometer problem than a gear problem. Seen something like this before that was corrected by making sure the cable was properly seated in the speedometer input and no kinks in the cable.