GM Service Manual Online
For 1990-2009 cars only

The engine unit number or date code is either laser etched or stamped into the engine block.

All engines are stamped with an eight digit engine identification number.

Figure 1:

4.3L Engine


Object Number: 174107  Size: SH
(1)Engine Identification Number
(2)Engine Identification Number
Figure 2:

4.8L, 5.3L, 6.0L Engine


Object Number: 174107  Size: SH
(1)Primary Engine Identification Location
(2)Secondary Engine Identification Location
Figure 3:

Engine ID


Object Number: 174106  Size: SH
(1)Source Code
(2)Month of Build
(3)Date of Build
(4)Broadcast Code