The Rear Axle

Contributed by John B (vegadad)

Reference: Building the V6/Vega by John Thawley

Over the manufacturing life Of the H-body, several Gear ratios were offered in either a 6.5" or 7.5" ring gear configuration. From 1971 through 1975 all of the rear axles were equipped with the weaker 6.5" ring gear. In 1976 and 77 some of the H-Bodied cars were equipped with either the 6.5" or 7.5" ring gear. H-bodied cars from 1978 and later all are equipped with the 7.5 ring gear configuration.

The identifying code is either located on a metal tag attached to a cover bolt or is stamped on the right front side axle tube about 3 inches outboard of the carrier, approximately 30 to 45 degrees above the horizontal.

FIELD IDENTIFICATION

FIRST 3 LETTERS ARE THE MINIMUM REQUIREMENT FOR IDENTO-PLATE

NK	B	218	D	W
RATIO CODE	MANUFACT. ID	JULIAN DATE	D = DAY SHIFT N = NIGHT SHIFT	LIMITED SLIP ID W = BORG WARNER E = EATON O = OLDS

NOTE: 1978 MODELS THE FOURTH CHARACTER INDICATES MODEL YEAR
FIFTH THROUGH SEVENTH, JULIAN DATE, THE EIGHTH CHARACTER, SHIFT CODE.

MANUFACTURER ID
B = BUICK
G = CHEVROLET GEAR AND AXLE
O = OLDSMOBILE
C = CHEVROLET BUFFALO
P = PONTIAC
K = GM OF CANADA, ST. CATHERINES (MCKINNON)
M = PONTIAC CANADA
W = CHEVROLET WARREN

1971-1974

ALL 6.5" RING GEAR

DESCRIPTION

TYPE DESIGNATION

DESCRIPTION

TYPE DESIGNATION

2.92 RATIO	HA	POSITRACTION 3.36 RATIO	HH
2.53 RATIO	HB	POSITRACTION 2.92 RATIO	HJ
3.36 RATIO	HC	POSITRACTION 3.73 RATIO (1974)	HMD
POSITRACTION 2.92 RATIO	HD	3.73 RATIO (1974)	HED
POSITRACTION 2.53 RATIO	HG	2.56 RATIO	HT
POSITRACTION 3.36 RATIO	HH	POSITRACTION 2.56 RATIO	HU
POSITRACTION 2.92 RATIO	HJ	2.93 RATIO	HP
POSITRACTION 2.93 RATIO	HW	3.42 RATIO	HF or HX
POSITRACTION 3.42 3.73 RATIO (1975)	HR HN	POSITRACTION 3.73 RATIO (1975)	HS

1975

ALL 6.5" RING GEAR

2.56 RATIO	DB or EB	2.92 RATIO	HA or HD
2.92 RATIO	DA or EA	2.93 RATIO	DX or EX DC or EC
3.42 RATIO	DE or EF DV or EV	3.73 RATIO	DF or EF

1976

6.5" RING GEAR

7.5" RING GEAR

2.53 RATIO	HB or HJ	2.56 RATIO	DY or EY
2.92 RATIO	HK or HM	2.93 RATIO	DX or EX
		3.42 RATIO	DU or EU
		3.73 RATIO	DT or ET
		4.10 RATIO	DS or ES

1977

6.5" RING GEAR

7.5" RING GEAR

2.92 RATIO	HK or HM	2.29 RATIO	DZ 2EA 2EZ
		2.56 RATIO	DY 2EB 2EY
		2.73 RATIO	DR ER
		2.93 RATIO	DX 2ED EX 2EW
		3.08 RATIO	2EJ 2ER
		3.42 RATIO	DU 2EF EU
		3.73 RATIO	2EG ET

1978

ALL 7.5" RING GEAR

2.29 RATIO	EA *EZ	2.56 RATIO	EB *EY
2.73 RATIO	EC *EX	2.93 RATIO	ED *EW
3.08 RATIO	EJ *ER	3.23 RATIO	EE *EV

1979

ALL 7.5" RING GEAR

2.29 RATIO	EA *EZ	2.56 RATIO	EB *EY
2.73 RATIO	EC *EX	2.93 RATIO	ED *EW
3.08 RATIO	EJ *ER

* INDICATES POSITRACTION

1980

ALL 7.5" RING GEAR

2.56 RATIO	2EB *2EY	2.73 RATIO	2EC *2EX
2.93 RATIO	2ED *2EW