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Service bulletin 18TR98A

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

The communication, as NHTSA indexes it (as of 2026-10-19)
TypeService bulletin
NHTSA id634282
Published by NHTSA2002-09-28
Manufacturer's number18TR98A
Manufacturer's date2002-06-01
Replaces26TR73E
NHTSA componentPOWER TRAIN:MANUAL TRANSMISSION

NHTSA's summary

VEHICLES MAY EXPERIENCE WATER AND/OR ETHYLENE GLYCOL IN TRANSMISSION OIL, ALL ALLISON TRANSMISSION MODELS.*JB

The document

No address for NHTSA's copy can be built for this communication. Ask the dealer for it by the manufacturer's number.

Components

Transmission and driveline, Manual transmission

Vehicles listed
GMC GM

Listing a model year does not mean every vehicle of it is concerned: the document says which.