GMC 1994 Yukon Owner's Manual page 344

GASOLINE ENGINES WITH HEAVY DUTY EMISSIONS
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MAINTENANCE SCHEDULE ff
*
An Emission Control Service
**
See "Explanation of Scheduled Maintenance Services" i t
A
A Noise Emission Control Service
W
Applicable only to vehicles sold in the United States
t
To determine the emissions classification of your engine,
Maintenance Chart" in this section.
TO404
7
the Index.
refer to "Selecting the Proper
7-10