Best Automatic Extension Housing Seals of 2026

Robert Reyes Avatar
Robert Reyes
Last Updated: Jan 10, 2026

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Automatic extension housing seals are an essential component in ensuring the proper function and longevity of a vehicle's transmission. These seals are designed to protect the transmission by preventing fluid leaks and keeping contaminants out. Made from high-quality materials, these seals are engineered to withstand the harsh conditions of the road and provide a reliable seal for extended periods. Automatic extension housing seals are available for a wide range of vehicles and are easy to install, making them a cost-effective way to keep your transmission running smoothly.

At a Glance: Our Top Picks

TOYOTA Oil Seal for Automatic Transmission Extension Housing Cover #TOP 1
TOYOTA Oil Seal for Automatic Transmission Extension Housing
ftb score rating icon 9.8
Mazda Manual Trans Extension Housing Seal Cover #TOP 2
Mazda Manual Trans Extension Housing Seal
ftb score rating icon 9.7
Pioneer Automatic Transmission Extension Housing Seal Cover #TOP 3
Pioneer Automatic Transmission Extension Housing Seal
ftb score rating icon 9.5

Top 10 Automatic Extension Housing Seals

#TOP 1

TOYOTA Oil Seal for Automatic Transmission Extension Housing

90311-40001
Regular
TOYOTA Oil Seal for Automatic Transmission Extension Housing Cover
Toyota Genuine Oil Seal for Automatic Transmission Extension Housing

This genuine Toyota Oil Seal is a high-quality OEM replacement for the Automatic Transmission Extension Housing of various Toyota models. It is compatible with several models, including the 4Runner, FJ Cruiser, Tacoma, and Tundra. The product is backed by a 1-year or 12k warranty, whichever comes first.

What We Like
High-quality OEM replacement.
Genuine Toyota product.
Compatible with various Toyota models.
#TOP 2

Mazda Manual Trans Extension Housing Seal

M507-17-335A
Mazda Manual Trans Extension Housing Seal Cover
Mazda M507-17-335A Manual Trans Extension Housing Seal

Get a genuine OEM factory part that is durable and of the best quality with the Mazda M507-17-335A Manual Trans Extension Housing Seal. This extension housing seal provides an exact fit and is not an aftermarket part. It is designed to fit your vehicle specifically and is ideal for those looking for a reliable and long-lasting part for their Mazda.

What We Like
Exact fit for your vehicle
Genuine OEM factory part
Durable and of the best quality
#TOP 3

Pioneer Automatic Transmission Extension Housing Seal

Pioneer Automatic Transmission Extension Housing Seal Cover
Pioneer 759009 Automatic Transmission Extension Housing Seal

This automatic extension housing seal has a part number of 759009 and a package weight of 0.077 kilograms. It measures 4.9 L x 9.9 H x 7.9 W (centimeters) and is made in the United States. This is a reliable option for those in need of an automatic extension housing seal.

What We Like
Reliable option for automatic extension housing seal needs
Compact and lightweight packaging
Made in the United States
#TOP 4

National 711009 Transmission Extension Seal

National
711009
National 711009 Transmission Extension Seal Cover
National 711009 Manual Transmission Extension Housing Seal

The National Transmission Seal is designed with a spring-loaded, multi-lip design that helps keep your vehicle's transmission secure and leak-free. This design ensures a tight fit, preventing fluid leaks and protecting your transmission from damage. It works well in a wide temperature range, from very cold -20°F up to 300°F, so you can trust it to perform in different weather conditions. Plus, it resists damage from EP lubricants, which means it lasts longer even when exposed to harsh chemicals. The seal also swells very little in hydrocarbon fluids, helping maintain its shape and function for reliable performance every time you repair your transmission.

What We Like
Spring-loaded multi-lip design
Wide temperature tolerance
EP lubricant protection
Low hydrocarbon fluid swell
#TOP 5

GM Genuine Parts Automatic Transmission Case Rear Extension with Seal

24224676
GM Genuine Parts Automatic Transmission Case Rear Extension with Seal Cover
GM Genuine Parts 24224676 Automatic Transmission Case Rear Extension with Seal

Introducing the GM Genuine Parts Automatic Transmission Case Rear Extension with Seal. Designed as a recommended replacement part for your GM vehicle's original factory component, this transmission case extension offers the quality, reliability, and durability you can trust. Manufactured to GM OE specification for fit, form, and function, it ensures a seamless installation and optimal performance. With its vehicle-specific fit, you can be confident that it will seamlessly integrate into your GM vehicle. The package dimensions of 24.765 H x 20.955 L x 23.495 W (centimeters) make it compact and easy to handle. Upgrade your transmission system with the GM Transmission Case Rear Extension and experience enhanced performance and longevity.

What We Like
Recommended replacement
Quality, reliability, durability
GM OE specification
#TOP 6

GM Transmission Case Extension Seal

24208660
Stock
GM Transmission Case Extension Seal Cover
GM Genuine Parts 24208660 Automatic Transmission Case Extension Seal

The GM Transmission Case Extension Seal, also known as the GM Transmission Seal, is a high-quality product manufactured by GM. With a reputation for excellence and a wide range of award-winning products, GM is a leading manufacturer in the automotive industry. Equipped with state-of-the-art technology, this seal has been specifically designed with professionals in mind. It is a perfect fit for vehicle-specific applications. The GM Transmission Seal ensures a tight and secure seal in the transmission case extension, preventing any leaks or damage. Its superior quality and precision make it a reliable choice for professionals and enthusiasts alike. Upgrade your transmission system with the GM Transmission Case Extension Seal and experience enhanced performance and durability.

What We Like
High-quality
Vehicle-specific fit
Precision design
#TOP 7

ATP CO-36 Automatic Transmission Extension Housing Seal

ATP CO-36 Automatic Transmission Extension Housing Seal Cover
ATP automotive CO-36 Automatic Transmission Extension Housing Seal

The ATP CO-36 Automatic Transmission Extension Housing Seal is designed to meet or exceed the original equipment specifications, ensuring high-quality performance. With a part number of CO-36, this extension housing seal is lightweight, weighing only 0.05 pounds, and has a compact size of 2.794 H x 9.144 L x 9.144 W (centimeters). It belongs to the category of Automatic Extension Housing Seals, assuring the users of its compatibility with their transmission system.

What We Like
High-quality performance
Lightweight and compact size
Designed to meet or exceed original equipment specifications
#TOP 8

National 710636 Auto Transmission Extension Housing Seal

National
710636
National 710636 Auto Transmission Extension Housing Seal Cover
National 710636 Auto Trans Ext. Housing Seal

The National Auto Trans Seal is designed to keep your vehicle’s transmission running smoothly. Its spring-loaded, multi-lip design helps create a tight seal, preventing leaks and protecting your transmission from dirt and debris. This seal works well in extreme temperatures, from as low as -40°F to as high as 400°F, so you can rely on it in different weather conditions. Plus, it is compatible with many types of fluids, making it a versatile choice for various transmission systems. Overall, this seal offers dependable performance that helps maintain your vehicle’s reliability.

What We Like
Spring-loaded multi-lip design
Wide temperature range
Fluid compatibility
High temperature resistance
#TOP 9

ACDelco 24286193 Transmission Extension Seal

24286193
ACDelco 24286193 Transmission Extension Seal Cover
ACDelco GM Original Equipment 24286193 Automatic Transmission Extension Housing Seal

The ACDelco Transmission Seal is a trusted replacement part designed specifically for GM vehicles. It matches the quality and reliability you expect from original GM equipment, ensuring your transmission stays well protected. This seal is made to fit perfectly and work just like the factory-installed part, so you can count on it to perform smoothly without hassle. By using this seal, you help maintain your vehicle’s durability and keep your transmission in good shape, saving you time and money on repairs down the road.

What We Like
GM recommended part
High quality and reliability
Durable construction
Exact factory specifications
#TOP 10

National 224464 Auto Transmission Extension Housing Seal

National
224464
National 224464 Auto Transmission Extension Housing Seal Cover
National 224464 Auto Trans Ext. Housing Seal

The National Auto Trans Seal is designed with a spring-loaded, multi-lip structure that helps keep your transmission fluids secure, preventing leaks and ensuring smooth operation. It works well in a wide temperature range, from -20°F to 300°F, so you can trust it in both cold and hot conditions. This seal is compatible with most oils and EP lubricants, which means it can handle higher operating temperatures without breaking down. Additionally, it resists swelling when exposed to hydrocarbon fluids, so you get a durable, reliable seal that lasts through tough conditions and keeps your vehicle running smoothly.

What We Like
Spring-loaded multi-lip design
Wide temperature range
Compatible with EP lubricants
Low swell in hydrocarbon fluids
Durable and reliable performance
Buying Guide Image

Frequently Asked Questions (FAQs)

1. Can you replace a transmission seal?

Replacing a transmission seal can be inexpensive and relatively easy for some seals. However, certain seals may require extensive dismantling, such as removing the gearbox, which is best left to a professional garage.

2. How many seals does a transmission have?

A transmission typically has two main external seals: the front seal and the rear seal. The front seal is located where the torque converter attaches to the transmission case, allowing fluid to flow but preventing leaks.

3. Can you drive with a bad transmission seal?

Although it may be possible to drive with a leaking transmission seal, it is not advisable. It is recommended to fix the problem as soon as possible.

4. How long does it take to fix a transmission seal?

The duration of fixing a transmission seal depends on the extent of the repair. Flushing the fluid, sealing, and recalibration can be completed within a day. Replacing shift solenoids may take a day or two. However, a full rebuild is a more time-consuming process, typically lasting three to four days.

5. How much does it cost to replace transmission seals?

The cost of repairing a transmission fluid leak varies. Replacing a seal can cost as little as $150, while replacing a torque converter can cost around $1,000. The precise cost depends on the specific vehicle and the extent of the repair.

Editor's Notes

During our automatic extension housing seal research, we found 24 automatic extension housing seal products and shortlisted 10 quality products. We collected and analyzed 2,459 customer reviews through our big data system to write the automatic extension housing seals list. We found that most customers choose automatic extension housing seals with an average price of $16.40.

The automatic extension housing seals are available for purchase. We have researched hundreds of brands and picked the top brands of automatic extension housing seals, including Toyota, Mazda, Pioneer Automotive Industries, National, GM GENUINE PARTS. The seller of top 1 product has received honest feedback from 135 consumers with an average rating of 4.9.

Written by
Robert Reyes Avatar

Robert Reyes is a dedicated writer from San Francisco with a bachelor of degree in mechanics and a bachelor of degree in marketing. He focuses on making some complicated topics simple and enjoys explaining complex and technical things in an easy-to-understand way.