1969 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 early model year, #3959038 has also been found with K88 cast date
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 ~ 10-bolt (L14/307)*
CB3.36:1 ~ 10-bolt
CC3.73:1 ~ 12-bolt
CD3.07:1 ~ 12-bolt Positraction
CE3.08:1 ~ 10-bolt Positraction
CF3.31:1 ~ 12-bolt Positraction (L34 & L35/396)*
CG3.36:1 ~ 10-bolt Positraction
CH2.73:1 ~ Positraction
CI3.73:1 ~ 12-bolt Positraction (L34/396 & L78/396)*
CJ2.56:1
CK2.56:1 ~ Positraction
CL2.56:1 ~ 10-bolt (L65/350-2)*
CM2.56:1 ~ Positraction
CN2.56:1 ~ 12-bolt (L48/350-4 & LM1/350-4)*
CO2.56:1 ~ 10-bolt (may or may not be Positraction, it's uncertain at this point)
CP2.73:1 ~ 10-bolt (L14/307)*
CQ2.56:1 ~ 10-bolt (L65/350-2)*
CS2.56:1 ~ Positraction
CT2.73:1
CW3.31:1 - 12-bolt (L35/396, L34/396 & L48/350-4)*
CX3.07:1 ~ 12-bolt (L35/396)*
CY3.07:1 ~ 12-bolt
CZ2.73:1
FH2.73:1
FI2.73:1 ~ Positraction
FJ3.08:1 ~ 10-bolt
FK3.08:1 ~ 10-bolt Positraction
FL3.36:1 ~ 10-bolt
FM3.36:1 ~ 10-bolt Positraction
FN3.55:1
FO3.55:1 ~ 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 ~ 12-bolt large ring gear (L48/350, L35/396)*
KE2.73:1 ~ Positraction, small ring gear (Note 1)
KF3.55:1 ~ 12-bolt Positraction, large ring gear (L35/396, L34/396, & L78/396)*  (Note 1)
KG3.08:1 ~ 12-bolt small ring gear (Note 1)
KH3.08:1 ~ 12-bolt Positraction, small ring gear (Note 1)
KI3.36:1 ~ 10-bolt
KJ3.55:1 ~ large ring gear (Note 1)
KK4.10:1 ~ 12-bolt Positraction (L78/396)*
KL3.36:1 ~ Positraction, small ring gear (Note 1)
KM4.56:1 ~ 12-bolt Positraction
KN3.55:1 ~ small ring gear (Note 1)
KO4.88:1 ~ 12-bolt Positraction
KP3.55:1 ~ Positraction, small ring gear (Note 1)
KQ4.10:1 ~ 12-bolt Positraction, heavy duty (COPO)*
KX3.07:1 ~ 12-bolt ~ Positraction

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, Protect-O-Plate warranty cards, or known engine/rear end combinations 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.


KD 2.73:1 ~ 12-bolt large ring gear, October 30, Buffalo, NY


KF 3.55:1 ~ 12-bolt Positraction, large ring gear February 14, Buffalo, NY


KJ 3.55:1 ~ 12-bolt, large ring gear March 03, Buffalo, NY


xx unknown ~ 12-bolt March 09, McKinnon Industries


CO 2.56:1 ~ 10-bolt Positraction April 24, Buffalo, NY

Courtesy Sam Aston
KF 3.55:1 ~ 12-bolt Positraction, large ring gear June 5, McKinnon Industries


CQ 2.56:1 ~ 10-bolt, July 02, Buffalo, NY

Casting Date Examples


Casting date example of L 17 8 for December 17, 1968


Casting date example of C 21 9 for March 21, 1969

Courtesy Pete and Wayne Jennings
Casting date example of D 16 9 for April 16, 1969
Courtesy Pete and Wayne Jennings


Another D 16 9 casting date


Casting date example of F 2 9 for June 2, 1969

Casting Numbers Examples




1967-1969 ~ Variations of casting number 3917124



1969 ~ Variations of casting number 3959038


1968-1969 ~ 3917123