speed correction

92 Dakota with 3.50 ratio and having correct tire size per door sticker, the speedo reads 7 - 9 miles fast..Anyone know of correct pinion and adpator that should be in the transmission ? I have factory service manual, but have not found that info.......any help would be appreciated, thanks Ken

if your tires and wheels are stock and your speedo is showing a faster speed than your actual speed.The speedo needs calibrating or it's junk and needs to be replaced.