Corvette C6 ZR1 differential in top condition, 18,000 km

For your inventory at Buy Mustang parts Ltd, a C6 ZR1 Differential with only 18,000 km is a “museum-grade” find. This specific unit is the pinnacle of factory C6 driveline engineering, designed to handle the 604 lb-ft of torque from the LS9 engine.

1. Technical Identification & Specs

The ZR1 differential is physically larger and internally stronger than the units found in the base C6 or Z06.

• OEM Part Number: #20931133 (Standard 3.42 Ratio).

• Key Feature: Features a 30-spline pinion gear (compared to the 27-spline in the Z06) and a massive 241mm ring gear.

• Cooling: Every ZR1 differential includes integrated cooling ports for a transmission/diff cooler loop, which is a requirement for high-speed track use.

• Case Design: Uses a specific high-strength aluminum alloy casing with additional webbing to prevent “case flex” under extreme loads.

2. Condition Report for “Top Condition” (18,000 km)

At this low mileage, the unit should be virtually indistinguishable from new. For your luxury listing, verify:

• Input/Output Shaft Play: There should be zero perceptible side-to-side or in-and-out play.

• Seal Integrity: At 18,000 km, the original factory seals should be bone-dry. Any “sweating” or oil film suggests the unit may have sat for a long period or was subjected to extreme heat.

• LSD Function: Perform a “break-away” torque test on the limited-slip clutches. They should provide firm, consistent resistance.

• Magnet Check: Remove the drain plug. A small amount of fine “fuzz” on the magnet is normal, but any visible metal flakes or “chunks” indicate gear surface fatigue.