Aluminum differential cover only (10-bolt corporate diff)

Years 1970–71 Models 1 Factory citations 2

Also described as Aluminum differential carrier & cover (~22 lb savings)

Documented applications

1970 Factory-verified

Factory option only on W-30/W-31/W-32; dealer-installed cover for other A-bodies; factory list: "Aluminum Rear Axle Carrier… Available Only with W30 or W31"

GM Heritage factory kit — 1970 Oldsmobile 442 Info Kit, p.231.
1971 Factory-verified

Availability beyond cover unknown for 1972; factory kit confirms 1971 as cover-only: "Aluminum Differential Cover"

GM Heritage factory kit — 1971 Oldsmobile 442 Info Kit, p.225.

This page aggregates every documented appearance of W-27 in the Oldsmobile reference. Confidence and citations are shown per application — the same code can be better documented in one year than another.