1968 Chevelle Rear Axle Identification

[ 1964 ] | [ 1965 ] | [ 1966 ] | [ 1967 ] | [ 1968 ] | [ 1969 ] | [ 1970 ] | [ 1971 ] | [ 1972 ]

The rear axle identification code consists of a two letter prefix indicating the gear ratio, four digits indicating the assembly date as month/day, and a single letter suffix indicating the manufacturing location. The identification code should be stamped on the bottom or font of right axle tube either adjacent to the carrier housing or about 8" - 10" inboard from the backing plates. The particular engine RPO code is listed in parentheses as found on build sheets.

Example: CG1025B decodes to CG ~ 3.36:1 Positraction, 1025 ~ Month [Oct] and Day [25], B ~ Buffalo (G=Chevrolet Gear & Axle, W=Warren, K=McKinnon Industries).

Casting Numbers:
12-Bolt Casting #3917124
10-Bolt Casting #
3917123

The casting numbers/letters on rear end housings may have either a prefix or suffix of "N" or "NF" and no reason has been found yet why they may have one or the other.

PrefixAxle Ratio
CA3.08:1
CB3.36:1
CC3.73:1
CD3.07:1 ~ Positraction
CE3.08:1 ~ Positraction
CF3.31:1 ~ Positraction (L35/396)*
CG3.36:1 ~ Positraction
CH2.73:1 ~ Positraction
CI3.73:1 ~ Positraction
CJ3.08:1
CP2.73:1
CR3.70:1 ~ Positraction
CU3.73:1 ~ Positraction w/Metallic Brakes
CV3.70:1
CW3.31:1
CX3.07:1
CY3.07:1 (L35/396)*
CZ2.73:1 (L35/396)*
FH2.73:1 ~ small ring gear (Note 1)
FI2.73:1 ~ Positraction, small ring gear (Note 1)
FJ3.08:1 (Base 230/base 307)*
FK3.08:1 ~ Positraction (L22/250 & 307)*
FL3.36:1 (L73/327)*
FM3.36:1 ~ Positraction
FN3.55:1 ~ small ring gear (Note 1)
FO3.55:1 ~ Positraction, small ring gear (Note 1)
FP3.70:1
K23.55:1
K33.55:1 ~ Positraction
K43.73:1
K53.73:1 ~ Positraction
K64.10:1 ~ Positraction
K74.56:1 ~ Positraction
K84.88:1 ~ Positraction
KA3.55:1 ~ small ring gear (Note 1)
KB3.55:1 ~ Positraction, small ring gear (Note 1)
KC2.73:1 ~ Positraction, small ring gear (Note 1)
KD2.73:1 ~ large ring gear (Note 1)
KF3.55:1 ~ Positraction, large ring gear (Note 1)
KJ3.55:1 ~ large ring gear (Note 1)
KK4.10:1 ~ Positraction
KM4.56:1 ~ Positraction
KO4.88:1 ~ Positraction
KW2.73:1 ~ w/Metallic Brakes
KX3.07:1 ~ Positraction
KY3.31:1 ~ Positraction
KZ3.31:1

Note 1:
Just what constitutes a 'small' ring gear or 'large' ring gear is uncertain. My Chevrolet Parts and Accessories Catalog, circa 1972, only shows the gear ratio service part numbers so it is quite possible one or the other was discontinued in favor of a 'service' part. Anyone with knowledge of the differences, please contact me so I can share the information with all.

Assembly Month - 1st and 2nd numbers
NumberMonthNumberMonth
01January02February
03March04April
05May06June
07July08August
09September10October
11November12December

Assembly Day - 3rd and 4th numbers
01...31

Rear Axle Assembly Plant - 5th letter

CodeAssembly Plant
BBuffalo, NY
GChevrolet Gear & Axle
WWarren, MI
KMcKinnon Industries

* Engine RPO code and size following the rear axle ratio are taken from build sheets or Protect-O-Plate warranty cards and may not reflect the only engine the rear axle codes came with. Where there are no RPO/engine information following the rear axle code only means I do not have documentation to verify them.

Axle Ratio Code Stamps


CY 0824B for 3.07:1 ratio, August 24, 1967, Buffalo plant


CF 0825B for Positraction 3.31:1 ratio, August 25, 1967, Buffalo plant


CW 0109B for 3.31:1 ratio, January 9, 1968, Buffalo plant


KF 0417B for Positraction 3.55:1 ratio, April 17 1968, Buffalo plant


CF 0522B for Positraction 3.31:1 ratio, May 22, 1968, Buffalo plant

Casting Date Examples


Casting date example of F 21 7 for June 21, 1967


Casting date example of B 18 8 for February 18, 1968


Casting date example of D 19 8 for April 19, 1968


Casting date example of E 8 8 for May 8, 1968

Casting Number Examples




1967-1969 ~ Variations of casting number 3917124