Axle Ratio & Identification Code

Rear axle ratio, differential type, manufacturer, and build date information is stamped on forward side of right axle tube. An identification code may be stamped on a metal tag attached to differential housing. Service parts identification label will have Regular Production Option (RPO) codes for rear axle identification. See Fig 1 . See AXLE RATIO IDENTIFICATION table.

NOTE: 7 1/2" ring and pinion gear has been replaced with 7 5/8" ring and pinion gear. Although axle housing assemblies look alike, internal components are different.

AXLE RATIO IDENTIFICATION

Application

Teeth Ring Gear/Pinion

RPO Code

Axle Code

Caprice & Impala SS Sedan

7 5/8" Ring Gear

2.73:1

41/15

GU2

2GA & 2GB

8 1/2" Ring Gear

2.73:1

41/15

GU2

2GH

2.93:1

41/14

GW9

⁽¹⁾ 2LQ

3.08:1

40/13

GU4

⁽²⁾ 2LW & ⁽¹⁾⁽²⁾ 2LX

3.23:1

42/13

GU5

2LR & ⁽¹⁾ 2ND

3.23:1

42/13

GU5

⁽¹⁾ 2LS & 2LT

3.23:1

42/13

GU5

⁽²⁾ 2LY & ⁽¹⁾⁽²⁾ 2LZ

Caprice Wagon

8 1/2" Ring Gear

2.56:1

41/16

GM8

2YN

2.93:1

41/14

GW9

2YF & ⁽¹⁾ 2YG

Roadmaster

Sedan

8 1/2" Ring Gear

2.56:1

41/16

GM8

2GC & ⁽¹⁾ 2GQ

Wagon

8 1/2" Ring Gear

2.56:1

41/16

GM8

2YN

2.93:1

41/14

GW9

2YF & ⁽¹⁾ 2YG

⁽¹⁾	Limited slip axle.

⁽²⁾	Police equipment.

Fig 1: Locating Rear Axle Identification Codes

Courtesy of GENERAL MOTORS CORP.