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Service bulletin SIL101K2K21

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 id10205140
Published by NHTSA2021-12-20
Manufacturer's numberSIL101K2K21
Manufacturer's date2021-11-12
NHTSA componentPOWER TRAIN; ENGINE AND ENGINE COOLING

NHTSA's summary

Announces updated design for the retaining ring for the balance piston retention in the C1 piston housing.

The document

The document is the manufacturer's. This site does not hold it. NHTSA files a document at one of these two addresses; we have not asked NHTSA which.

Components

Engine, Transmission and driveline

Vehicles listed
ALLISON TRANSMISSION

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