my father inlaw has a 69 coupe, we are trying to figure out the rear end ratio, the numbers that are on the bottom of the differential are 2-az-2-10-69w any one out there that can decifer this????? thanks

 

I don't have a list of the rear axle codes handy but you can get a ball park figure without opening the rear. Jack up the rear of the car and put it in neutral. Using chalk, mark the driveshaft and a corresponding spot on the front of the carrier (housing). Now mark a spot on your left rear tire and a spot on the floor. Turn the wheel counterclockwise one turn and count the number of turns the driveshaft makes. A little over three turns = 3.08. A little less than three and a half turns = 3.36. Three and three quarters turn = 3.73 and so on. Do the procedure at least twice to check your results. This method is actually more accurate than decoding the axle numbers. These cars have been rebuilt many times over the years and they may not have the original ratio gears in them.