1. Thermostats & Parts For Sale
  2. sku: 9980911691677641
  3. GM 3860303

GM 3860303 Dual Thermostat Housing General

fits model: 366, 427. make: Chevrolet. year: 1966-72.

3860303 General Motors Oem 1966-72 Gm Chevrolet 366 / 427 Dual Thermostat Housing Bbc

( Brand: Gm ), ( Manufacturer Part Number: 3860303 ), ( Type: Thermostat Housing ), ( Material: Metal ), ( Vintage Part: Yes ), ( Country/region Of Manufacture: United States ), ( Placement On Vehicle: Front )

Review GM General Motors Oem Chevrolet Dual Thermostat Housing Bbc fits 366 427 1966-72

Introducing the 3860303 1966-72 GM Chevrolet 366 427 Dual Thermostat Housing BB, a high-performance upgrade for your classic Chevrolet engine. This thermostat housing is specifically designed for engines equipped with the 366 cubic inch (5.9L) 427 V8, and is a must-have for enthusiasts seeking improved cooling efficiency and durability.

The housing itself is meticulously crafted from premium materials, ensuring a robust and reliable fit in your engine bay. Its billet aluminum construction not only offers superior heat conductivity, but also contributes to the sleek and polished appearance that complements the classic lines of your Chevrolet.

One of the most significant advantages of this dual thermostat housing is its ability to accommodate two thermostats. This innovative design allows for separate cooling circuits for the engine and transmission, ensuring optimal operating temperatures for both components. The result is reduced thermal stress on critical engine parts, improved fuel efficiency, and extended engine life.

The housing is designed with a bolt-on installation in mind, making it a straightforward addition to your engine. It features OEM-style mounting points and comes complete with all necessary hardware for a hassle-free installation process. Additionally, the housing's precision machining guarantees a perfect fit, reducing the risk of leaks or other complications.

By upgrading to this 3860303 1966-72 GM Chevrolet 366 427 Dual Thermostat Housing BB, you're not only enhancing the performance and reliability of your classic Chevrolet, but also adding a touch of modern engineering to its timeless design. This is an essential upgrade for any dedicated enthusiast looking to take their Chevrolet to the next level.

Buying a 1966-1972 GM Chevrolet 366/427 dual thermostat housing for BB (Big Block) engines can be a consideration for those looking to restore or build high-performance versions of these classic vehicles. Here are some pros and cons that might help in making an informed decision.

Pros:

1. Improved Cooling System: A dual thermostat housing allows for better engine temperature management. It keeps the engine cool during hard driving and maintains optimal operating temperature during normal conditions. This can lead to improved engine performance and longevity.

2. Authentic Restoration: For those restoring a classic Chevy, a dual thermostat housing is an authentic and desirable upgrade, as it was an option offered during the production years in question.

3. Enhanced Appearance: The dual thermostat housing can add a touch of elegance and distinction to the engine bay, making it a desirable cosmetic upgrade for enthusiasts.

Cons:

1. Cost: A dual thermostat housing is a specialized part, and as such, it can be more expensive than a single thermostat housing. It may require a significant investment, particularly for those on a tight budget.

2. Installation Complexity: Installing a dual thermostat housing can be a challenging process, requiring a high level of mechanical skill and knowledge. It may also require additional parts or modifications to the cooling system.

3. Availability: Finding a high-quality, authentic dual thermostat housing may be difficult, as they were not mass-produced. This could lead to long waiting times or the need to source an aftermarket alternative, which may not be of the same quality.

In conclusion, a 1966-1972 GM Chevrolet 366/427 dual thermostat housing for BB engines offers several advantages, including improved cooling system performance, authenticity, and enhanced appearance. However, it also comes with some drawbacks, such as a higher cost, installation complexity, and availability challenges.

Based on the information provided, it is recommended to thoroughly research the market, assess the specific needs and resources, and carefully consider the pros and cons before making a decision to purchase a 1966-1972 GM Chevrolet 366/427 dual thermostat housing for BB engines. If the decision is made to proceed, it is advisable to seek the assistance of a qualified mechanic or restoration specialist to ensure a successful installation.

Details:

Again, check to make sure that this will fit your application. Check the pictures and make sure that it fits your application. Please see the pictures as they are part of. Item is for sale locally, so I reserve the right to end listing early.

This would be a great item to finish off that restoration and plenty of life left in it. It may fit other years and motors. Look the pictures over and judge for yourself. What you see is what get.

This is an original part that in pretty good condition for its age, but there some pitting and wear typical of exposure to antifreeze. It is straight out of the blast cabinet from so what you see bare metal, which should make prep for painting or polishing easier. 366, 427 etc Chevrolet Cast Iron Dual Thermostat Housing as shown.It has manufacturers stamping of GM and 3860303 shown.

part #: 3860303 prices

  • $45.00-$89.95

specifications theostapa:

  • for models: 366, 427
  • for makes: Chevrolet
  • for years: 1966-72
  • brand: Gm
  • mpn: 3860303
  • type: Thermostat Housing
  • material: Metal
  • vintage part: Yes
  • country/region of manufacture: United States
  • placement on vehicle: Front

payments theostapa:

  • wallet: Paypal
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  • credit card: Discover

returns theostapa:

  • policy: No Returns

seller theostapa:

  • city: Webster City, Iowa
  • rating: 99.7%
  • # reviews: 2151

general theostapa:

  • condition: Used
  • Car Truck Parts Accessories > Engine Cooling Components > Thermostats Housings

shipping theostapa:

  • carrier: USPS
  • transit: 4-9 Days
  • type: Fixed
  • service: USPS Ground Advantage
  • class: Standard
  • cost: $12.00

offer theostapa:

  • best offers: True
  • availability: In Stock
  • started: August 16, 2025
  • quantity: 1
  • options: Ship-to-home
  • sold: 0
for models: 366, 427, for makes: chevrolet, for years: 1966-72, type: thermostat housing, vintage part: yes, country/region of manufacture: united states, placement on vehicle: front,
category: auto parts > car truck parts accessories > engine cooling components > thermostats housings, material: metal, sku: 9980911691677641,
Gm 3860303 Is Similar To:
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2 offers $45.00–$89.95 USD
  • Used. Offer #1 priced at $89.95 + $12.85 shipping estimate = $102.80* total. 1966-72 BBC 366 427 DUAL THERMOSTAT HOUSING IN GOOD CONDITION.+$12.85 shipping
  • Used. Offer #2 priced at $45.00 + $7.78 shipping estimate = $52.78* total. This water outlet housing, with part number 30160, ensures proper engine cooling by providing a seal for the water outlet on the V8 engine.+$7.78 shipping

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