Axle ratio

I imagine that this has been asked and answered before, but I can not locate it.

To the best of my knowledge my 71 Duster 318V8-- A904 auto tranny and rear end are original to the car. There have been no modifications to any of them. The tires are 14" with a diameter of 24 inches.
Will someone tell me the Axle Ratio of this vehicle?
My speedo runs appx 13 mph high at 60 mph and I want to replace the speedo pinion gear to correct it, It came with a 29 tooth pinion