Thermostat housing O-ring for the 1988 to 1998 Chevrolet and GMC C/K (GMT400) with the 5.0 or 5.7 V8.

Part numbers

GM 12551507 (replaces 12553106). Genuine GM part.

Fits

1988 to 1998, 5.0/5.7 V8, both TBI and Vortec, this one part covers the whole range.

Why it matters

This gasket hardens with heat cycling and is a common source of coolant seepage at the housing, often before the housing itself shows any real wear. Cheap to replace and worth doing any time the housing or thermostat comes off.

What you get

One thermostat housing O-ring, genuine GM part.

If you're not certain this is the right part, drop us your VIN before ordering. We'd rather check it now than have you sending it back.