Gage package, with tachometer

Years 1984, 1986–88 Models 1 Factory citations 3

Also documented for Chevrolet

Documented applications

Firebird — Third generation (1982–1992)

1984, 1986–1988 Factory-verified

3rdgenformula reads the rally gauge cluster on the base Firebird; Firebird years: thirdgen.org label decodes 1984, 1986; 3rdgenformula option pages 1987–1988; shared F-body code; cited from the Camaro kits

GM Heritage factory kit — 1984 Chevrolet Camaro, p.4.
GM Heritage factory kit — 1986 Chevrolet Camaro, p.22.
GM Heritage factory kit — 1987 Chevrolet Camaro, p.15.

This page aggregates every documented appearance of U21 in the Pontiac reference. Confidence and citations are shown per application — the same code can be better documented in one year than another.