PF was used as an axle code for 12 bolt posi unit (yours is a 10 bolt) for Camaro for 67, 68, and 69. In 1967 and 68 it was a 3.31:1 ratio and in 1969 it was a 2.73:1 ratio. Since yours is a 10 bolt, must be from some other application. Following is the axle decode section from the CRG main web site under drivetrain decoding: http://www.camaros.org/drivetrain.shtml#RearAxleNumbers
No idea what code CG is - something other than 1st Gen Caimaro.