Usually this figure is around 70%. I know that in my '82 Vette it was 68% or .68 of the final drive gear ratio which was 2.72 in that car. I changed those out for 3.73's. Our Mustangs have 3.27's stock. So in 3rd gear we have a 1:1 ratio, or, 3.27. What is it when in OD? I need a manual as my car did not come with one. I have heard it is 70% or the same as GM which as I said was 68%. Can anyone provide me with this figure? It should be in the owners manual. I cannot find this info in the Haynes manual I bought. The info would be much appreciated. Mark