1977–1987 Chevy/GMC Truck Radiator | Cold Case GMT556A21 Options

Choose a Cold Case GMT556A21-family aluminum radiator for your 1977–1987 Chevy/GMC truck. These are the 21-inch overall-height versions, with OE-style stamped tanks and two rows of 1.25-inch tubes. Match the radiator version to your engine, hose connections and radiator support before ordering.

Choose your radiator version

• GMT556A21 — Silver / polished: Standard configuration for automatic transmission. Upper hose: 1.50 inches. Lower hose: 1.75 inches.
• GMT556A21B — Black Night Rider: Powder-coated black, automatic-transmission configuration. Upper hose: 1.5 inches. Lower hose: 1.75 inches. Transmission cooler fitting: 5/16-inch inverted flare. Supplier lists compatibility with the factory fan shroud. For 4WD/1.75-inch outlet vehicles, the supplier lists lower hose Gates 20694 or Dayco 70664.
• GMT556A21-1 — Polished, smaller hose connections: Automatic-transmission configuration with a 1.25-inch upper hose and 1.5-inch lower hose. Transmission cooler fitting: 5/16-inch inverted flare.
• GMT556A21LS — Polished, LS swap: Includes an LS-swap steam port, with 1.50-inch upper and lower hose connections. Supplier lists automatic-transmission applications and recommends an external transmission cooler.

Shared construction and dimensions

• 100% TIG-welded aluminum construction
• Two rows of 1.25-inch tubes
• OE-style stamped tanks
• 16 fins per inch
• Pressure tested
• Core height: 18.8 inches
• Core width: 28.35 inches
• Overall height: 21 inches
• Overall width: 34.33 inches
• Overall thickness: 3 inches

The polished versions use corrugated fins for additional surface area and thermal transfer.

Fitment notes

For 1977–1987 Chevy/GMC truck applications using the tall, 21-inch radiator configuration. Confirm radiator-support dimensions, engine/accessory clearance, mounting points, hose sizes and transmission-cooling requirements. These configurations are not interchangeable solely because they share overall dimensions.

For the shorter 19-inch overall-height version, refer to Cold Case GMT556A rather than selecting a GMT556A21 version.

Supplier warranty: Limited Lifetime Warranty.

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