1969 SS 396

Rear End Gear Ratio/Codes

All 1969 SS 396 Chevelles were equipped with a 12-bolt rear end. The casting number to look for is #3917124.

Prefix	Axle Ratio
CC	3.73:1 ~ 12-bolt
CD	3.07:1 ~ 12-bolt Positraction
CF	3.31:1 ~ 12-bolt Positraction (L34 & L35/396)*
CH	2.73:1 ~ Positraction⁽²⁾
CI	3.73:1 ~ 12-bolt Positraction (L34/396 & L78/396)*
CJ	2.56:1
CK	2.56:1 ~ Positraction
CM	2.56:1 ~ Positraction
CS	2.56:1 ~ Positraction
CT	2.73:1⁽²⁾
CW	3.31:1 - 12-bolt (L35/396, L34/396 & L48/350-4)*
CX	3.07:1 ~ 12-bolt (L35/396)*
CY	3.07:1 ~ 12-bolt
CZ	2.73:1⁽²⁾
FH	2.73:1⁽²⁾
FI	2.73:1 ~ Positraction⁽²⁾
FN	3.55:1
FO	3.55:1 ~ Positraction
KA	3.55:1~ small ring gear ⁽¹⁾
KB	3.55:1 ~ Positraction, small ring gear ⁽¹⁾
KC	2.73:1 ~ Positraction, small ring gear ⁽¹⁾⁽²⁾
KD	2.73:1 ~ 12-bolt large ring gear (L48/350, L35/396)*
KE	2.73:1 ~ Positraction, small ring gear ⁽¹⁾⁽²⁾
KF	3.55:1 ~ 12-bolt Positraction, large ring gear (L35/396, L34/396, & L78/396)* ⁽¹⁾
KG	3.08:1 ~ 12-bolt small ring gear ⁽¹⁾
KH	3.08:1 ~ 12-bolt Positraction, small ring gear ⁽¹⁾
KJ	3.55:1 ~ large ring gear ⁽¹⁾
KK	4.10:1 ~ 12-bolt Positraction (L78/396)*
KM	4.56:1 ~ 12-bolt Positraction
KN	3.55:1 ~ small ring gear ⁽¹⁾
KO	4.88:1 ~ 12-bolt Positraction
KP	3.55:1 ~ Positraction, small ring gear ⁽¹⁾
KQ	4.10:1 ~ 12-bolt Positraction, heavy duty (COPO)
KX	3.07:1 ~ 12-bolt ~ Positraction

⁽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.

⁽²⁾ This gear ratio was available in both the 10-bolt and 12-bolt rear end. I have no documentation showing which code goes to which.

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

Rear Axle Assembly Plant - 5th letter
Code	Assembly Plant
B	Buffalo, N.Y.
G	Chevrolet Gear & Axle
W	Warren, MI.
K	McKinnon Industries

Three different 396 cid engines were available, the 325-hp (RPO L35), 350-hp (RPO L34) and 375-hp (RPO L78)

See the engines page for engine/transmission breakdown.

Transmission

The 1969 SS 396 came standard with a floor-shifted manual 3-speed transmission. Three optional Muncie 4-speed manual transmissions were available, a wide ratio (RPO M20), a close ratio (RPO M21), and the heavy duty close ratio (RPO M22). The 2-speed Powerglide or 3-speed TH400 automatic transmission could be ordered behind either the base 325 hp engine or the optional 350-hp engine. The L78 engine could now be ordered with a manual transmission or the TH400 automatic transmission. COPO Chevelles were optioned with either the heavy duty Muncie (M22) manual transmission or a heavy duty TH400 automatic transmission.

Power Teams - Sport Coupe/Convertible

El Camino

TH400 Turbo-Hydramatic

Several TH400 automatic transmissions were used depending on the horsepower rating of the engine. These can be identified by (1) their color and (2) their code. This tag is riveted to the passenger side of the transmission and contains valuable data if you're concerned with originality. The number stamped in the middle (such as the 228 on the first example) is the Julian date starting on January 1, 1968. So a Julian date of 228 is the 228th day counting from January 1, 1968 or August 15, 1968 (remember 1968 is a leap year).

If the Julian date is 366 or greater then the transmission was built in 1969 like the last example with a Julian date of 395. Subtract 366 from 395 and you get 29, or January 29, 1969.

The 4- or 5-digit number on the bottom right of the tag is simply the transmission's serial number and of no consequence as far as dating it goes.