Positraction Rear Axle, all ratios

Years 1963–79 Models 3 Factory citations 8

Also described as Positraction Rear AxleOptional Rear Axle RatioPositraction

Documented applications

Corvette (C1 / C2)

1963 Factory-verified

$43.05; 17,554 built

GM Heritage factory kit — 1963 Chevrolet Corvette, p.8.
1964 Factory-verified

$43.05; 18,279 built

GM Heritage factory kit — 1964 Chevrolet Corvette, p.17.
1965 Factory-verified

$43.05; 19,965 built

GM Heritage factory kit — 1965 Chevrolet Corvette, p.14.
1966 Factory-verified

$42.15; 24,056 built

GM Heritage factory kit — 1966 Chevrolet Corvette, p.14.
1967 Factory-verified

$42.15; 20,308 built

GM Heritage factory kit — 1967 Chevrolet Corvette, p.57.

Corvette (C3)

1968 Factory-verified

$46.35; 27,008 built (94.6% of production)

GM Heritage factory kit — 1968 Chevrolet Corvette, p.7.
1969 Factory-verified

$46.35; 36,965 built

GM Heritage factory kit — 1969 Chevrolet Corvette, p.5.
1970 Factory-verified

$12.65; 2,862 built (code repurposed — Positraction was now standard)

GM Heritage factory kit — 1970 Chevrolet Corvette, p.5.

Impala / Full-Size

1963–70s (varies) Single-source

This page aggregates every documented appearance of G81 in the Chevrolet reference. Confidence and citations are shown per application — the same code can be better documented in one year than another.