Differential tag info

3.45 = ratio.

1138 = number of teeth, 11 on pinion 38 on ring.

A = Exchange unit.

S = Limited slip.  

N = Heavy duty , not for US. 

V = Extra heavy duty , not for US.

4002 = Date code for new differential.

400 = Date code for exchange.

e.g. S3.45 4002  = New limited slip differential 3.45:1 ratio.   

e.g. 1138 A 405S = Limited slip 38:11 exchange unit.

The date codes are used exclusively for ID in the plant.

E30 M3 Repair Manual V2.7.  Copyright ©1999-2001 Koala Motorsport & Brett Anderson