1964 Chevelle Rear Axle Identification

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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 front left or right axle tube either adjacent to the carrier housing or about 8" - 10" inboard from the backing plates.

Example: YB 1025 decodes to YB ~ 3.36:1, 1025 ~ Month [Oct] and Day [25]

Casting Numbers:
10-Bolt Casting #3839390N

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
LA3.08:1 ~  3 or 4-speed
LB3.36:1 ~  3 or 4-speed
LG3.08:1 ~  Positraction
LH3.36:1 ~  Positraction
YA3.08:1 ~  3 or 4-speed
YB3.36:1 ~  3 or 4-speed
YG3.08:1 ~  Positraction
YH3.36:1 ~  Positraction
ZA3.08:1 ~  found with Powerglide transmission
ZB3.36:1 ~ 
ZC3.08:1 ~  w/Metallic Brakes
ZD3.36:1 ~  w/Metallic Brakes
ZE3.08:1 ~  Positraction w/Metallic Brakes
ZF3.36:1 ~  Positraction w/Metallic Brakes
ZG3.08:1 ~  Positraction
ZH3.36:1 ~  Positraction
ZJ3.70:1 ~  w/Overdrive
ZK3.70:1 ~  Positraction
ZL3.70:1 ~  w/Metallic Brakes
ZM3.70:1 ~  Positraction w/Metallic Brakes
Assembly Month - 1st and 2nd numbers *
NumberMonthNumberMonth
01January02February
03March04April
05May06June
07July08August
09September10October
11November12December
* It's not unusual for the month to be a single digit number

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

Rear Axle Assembly Plant - 5th letter

CodeAssembly Plant
BBuffalo ~  New York
GChevrolet Gear & Axle
WWarren ~  Michigan
KMcKinnon Industries


ZA 1001 ~ 3.08:1 - October 1

09/06/2011
ZA ~ 3.08:1 ~ June 23

Casting Date Examples


Casting date example of H 20 4 for August 20, 1964

Housing Casting