The gears are in a Speedway motors box with a code of 916-81204. The gears are ten splined. The smaller gear has 23 teeth. The larger one has 25 teeth. The outside of the box is marked "5.28". The gears are stamped C528447-1H6 and C528447-2H6.
SCS Gears 1037 Quick Change Gear Set Sportsman Set 37 10 Spline 4.11 Ratio
Winters 4408 Quick Change Gear Set 4400 Series Set 8
SCS Gears 25 Quick Change Gear Set Professional Series Set 25 10 Spline
SCS Gears 1023 Quick Change Gear Set Sportsman Set 23 10 Spline 4.11 Ratio
SCS Gears 12 Quick Change Gear Set Professional Series Set 12 10 Spline
SCS Gears 1028 Quick Change Gear Set Sportsman Set 28 10 Spline 4.11 Ratio