speedo

My 76 duster with a360 and 904 trans reads 10 mph over, how many teeth do I need to go up? don"t know whats in it right now. thanks again guys. PS who sells new ones?

What size are your rear tires?

What axle & gear are you using?

Which speedo gear is in your transmission now?

Torqueflite Patty would probably have the speedometer pinion gear you need.