Parts Catalog No 692 1958-69 seems to indicate the following for gear and pinion units 1958-64, 3.08 ratio - 12 pinion, 37 gear teeth, part #3758549 1958 -64, 3.36 ratio - 11 pinion, 37 gear teeth, part # 3798437 1958-64, 3.55 ratio - 9 pinion, 32 gear teeth, part # 3795479
Also found a detailed 1966 Differential Identification Code Table listing about 75 axle codes. Not sure if this applies to years other than 1966 . The code can be found stamped 1/4" high on the bottom of the right hand axle tube approximately 3" from the carrier. DA = 3.08 DI = 3.36 DQ = 3.55