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Heating and Cooling› Radiators

Cold Case

21-Inch Aluminum Performance Radiator

$828.65 $690.54 Save $138.11

SKU: GMT556A21LSK

Special Order
Special Order
Ships in 4–6 weeks
Free Shipping over $200
$100 Minimum Order
30 Days Return
INSTALL DIFFICULTY
DIY PRO SHOP

Moderate — 2–4 hours

Overview

The Cold Case GMT556A21LSK is a 21-inch aluminum performance radiator designed for 1977-1987 Chevy/GMC trucks with an LS swap and automatic transmission. It features 100% TIG-welded aluminum construction with polished OE-style tanks and two 1.25-inch tubes. The radiator includes corrugated fins with 16 fins per inch for increased surface area and thermal transfer.
Show original supplier description
The Cold Case GMT556A21LSK is a 21-inch aluminum performance radiator specifically engineered for 1977-1987 Chevy/GMC trucks undergoing an LS engine swap with an automatic transmission. This radiator boasts a robust 100% TIG-welded aluminum construction, ensuring durability and efficient heat dissipation. Its polished OE-style tanks provide a classic aesthetic, while the dual 1.25-inch tubes and 16 fins per inch with corrugated design maximize surface area for superior thermal transfer. This performance radiator is designed as a direct fit replacement, simplifying installation. It features a dedicated steam port crucial for LS swap applications and comes pressure-tested for reliability. The oversized 2-row design is highlighted as being more effective for cooling than traditional 3 or 4-row aluminum radiators. For optimal performance, this unit includes dual 12-inch fans and a shroud to enhance airflow.
Vehicle Symptoms
  • Engine temperature gauge rising above normal
  • Coolant leaking from radiator or hoses
  • Overheating during highway driving or idle
  • Sweet smell of coolant in the cabin or engine bay
  • Visible rust or sludge in the coolant reservoir
Diagnostic Codes
  • P0217 – Engine Coolant Overtemperature Condition
Relevant Conversations
  • 1977 Chevy C10 LS swap radiator options
  • C10 overheating after LS swap forum
  • Cold Case GMT556A21LSK review
  • 21 inch aluminum radiator for square body GM truck
  • Best radiator for 1985 GMC K2500 LS swap
  • P0217 code on swapped LS engine
  • LS swap cooling system upgrade 1977-1987
  • Direct fit radiator for Chevy truck automatic transmission
  • Comparing Cold Case vs stock radiator cooling
  • Will this radiator work with my 1982 C20 LS swap?

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

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Specifications

BrandCold Case
Part NumberGMT556A21LSK
CategoryHeating and Cooling
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Returns & Fitment

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

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Shipping

Orders are processed in 1–3 business days. In stock parts ship promptly from our partner network. Special-order items either aren’t currently stocked or are built to your spec — expect 4–6 weeks. If a part goes on backorder while your order is in the queue, we’ll reach out and work through discounted alternatives together.

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