MOPAR 28 Tooth Speedo Gear

That doesn't go in the speedometer, it goes in the transmission tail shaft housing, and turns the speedometer. I 'think' but not positive that 904 and 727 speedo gears interchange. You need to match the gear above to your rear end gear ratio and rear tire size. The charts in the thread below will help figure it out. Good luck with sale.
Speedometer Gear Charts - Clarification/Differences | For A Bodies Only Mopar Forum