UNIVERSAL-FIT DESIGN – Three-piece steel transmission tunnel provides the clearance needed for larger modern transmissions while fitting a wide range of classic vehicle applications., DURABLE STEEL CONSTRUCTION – Formed from 18-gauge cold rolled steel for strength, weldability, and easy integration into your vehicle’s existing floor pan and firewall., PRECISION LASER CUT & PRESS FORMED – Laser-cut panels ensure accuracy, while press-formed contours save hours of fabrication time compared to scratch-built sheet metal., MADE FOR MODERN TRANSMISSIONS – Offers clearance for popular large gearboxes such as the GM 4L80E, Tremec Magnum, and other overdrive or manual transmission conversions., EASY CUSTOM INSTALLATION – Includes bellhousing, main, and tail sections designed for trimming and weldin Universal Fit Three Piece Steel Transmission Tunnel Kit Sku # 91089655 Mfr. Part # 91089655 Condition New Brand Speedway Motors Sold Each Details
- Made from 18 gauge cold rolled steel for easy integration to your floor pan
- Laser cut and press bent for ease of fabrication to your fitment needs
- Kit features three pieces that can be trimmed as needed and then welded
- Bellhousing, main section, and tail section sized for large automatic transmissions
- Will also work for larger manual transmissions like Tremec Magnum six speed
- Requires welding for final installation to floor pan and firewall
- Shifter/shift cable opening placement is up to end user/fabricator to locate
Don’t Let a Factory Transmission Tunnel Stop You from A Modern Transmission Swap
Most any car built before the 21st century utilized a 3- or 4-speed automatic or a 5-speed manual. If you really roll the calendar back, there were even 2-speed autos and 3-speed manuals installed in the trans tunnel of various rides. These transmissions were relatively demure in stature, allowing the manufacturer to utilize a small transmission tunnel in their floor pan stamping. This provided more leg room, but also allowed bench seats and bucket seats with consoles to fit more easily as well.
Today, many enthusiasts are looking for ways to extend their driving range with overdrive transmissions. From modern electronically controlled 4-, 6-, or even 10-speed automatics, to double overdrive 6-speed manual transmissions, these transmissions require large cases to hold those extra gears, and in many cases electronic controls. Installing these larger than life transmissions not only require some sort of transmission swap crossmember, but in many cases requires modification to the factory transmission tunnel. Cutting away the factory transmission tunnel sheet metal to fit a wider and taller transmission means also having to fabricate a new replacement tunnel. Our three piece transmission tunnel kit makes this task a breeze, as much of the fabrication work is already handled.
Laser Cut and Press Formed Transmission Tunnel Saves Fabrication Time
We know that not everyone is a sheet metal savant and that fabrication of something like transmission tunnel sheet metal can be a frustrating experience to say the least. It takes numerous sheetmetal tools to make a proper tunnel or even to pie cut and raise the factory tunnel. Our universal transmission tunnel kit is laser cut, and press formed from automotive grade 18 gauge cold rolled steel, just like the rest of your vehicle’s floor pan. The kit is designed to provide ample transmission tunnel clearance and has been tested to fit such “big boy” transmissions as the GM 4L80E four-speed automatic overdrive transmission and Tremec’s Magnum six-speed (often referred to as the T-56 or TR6060).
To make installation easier, the kit is comprised of three main parts. The forward most section is the bellhousing section, followed by the main body section, and finally the tail section. This allows the end user to trim any or all three pieces as needed for the best fit. Once trimmed to fit the three sections are then welded together and then to the floorpan and firewall to make a strong replacement transmission tunnel that offers generous clearance for the transmission swap. Being a universal component, the installation of a manual shifter opening or pass-through hole for an automatic shifter cable will be up to the end user and the type of shifter used.
Due to the universal oversized design some molded carpets may not fit properly, however using bulk carpet in a “cut and sew” pattern or carpet sections with serge edging will provide for a superior finished look and custom fit if you’re opting for a carpeted floor. Many classic cars, including the Corvette, used such carpets. A local upholstery or trim shop can assist. The same consideration must be made for factory or aftermarket consoles. Some consoles may require trimming of their plastic housings to fit your new custom transmission tunnel properly as well. Much of this is “hot rodding 101” but it is being mentioned for consideration.
Universal Transmission Tunnel Kit Dimensions:
- Bellhousing Section: 22-3/16-inch wide by 15-1/16-inch tall tapering down to 15-5/8-inch wide by 10-1/16 tall, 12 inches long
- Main Body Section: 15-5/8-inch wide by 10-1/16 tall, 11 inches long
- Tail Section: 15-5/8-inch wide by 10-1/16 tall tapering down to 7-3/16-inch wide by 8-1/16 tall, 12 inches long
- Overall Length: 35 inches long
Specs Material Thickness .0478" Overall Length 35.00" Overall Width 22.19" Material Type Steel Finish Bare Sold in Quantity Each Reviews I would buy this product again. Rated by Jose on December 19, 2025
Summary: very easy to use, made the fabrication of the transmission tunnel very easy.
Yes, I recommend this product.
Related Items / Suggested Parts LizardSkin Sound Control Application Kit Flatline Barriers FB20 Heat Barrier/Sound Deadening, 18 x 32 TorqLink™ Universal Adjustable Transmission Crossmembers Universal GM Transmission Crossmembers with Adjustable Mount Kit DEi 050503 Floor/Tunnel Shield II, Heat/Sound Insulation, 4 Ft x 42 In DEi 050501 Floor/Tunnel Shield II, Heat/Sound Insulation, 2 Ft x 21 In SoloSwap® GM 4L80E Swap Mock Up Transmission SoloSwap® T-56/Magnum/TR-6060 6-Speed Mock Up Transmission Kit SoloSwap® Allison 1000 Mock-Up Transmission SoloSwap® Tremec T-56 Swap Adjustable Mock Up Bellhousing Hurst 69510000 Sheet Metal Tunnel Patch, Magnum 6-Speed Tech Support We're here to help before and after your purchase. If you have a question or need assistance with one of our products, please contact us through Messaging and a knowledgeable Speedway Motors team member will be happy to help. About Speedway Motors is America’s Oldest Speed Shop® and has been a trusted source for specialty rodding and racing products and friendly expert advice for more than 74 years. Founded in 1952 by “Speedy” Bill Smith – a racer and street rodder himself – Speedway has grown from a one-man operation to become the world’s largest manufacturer, distributor and retailer of street rod and racing products. Our industry-leading fast delivery is the result of same-day shipping from our state-of-the-art, centrally located 500,000 sq. ft. headquarters. Speedway’s size offers customers unmatched product selection and low pricing, while our excellent technical support and customer service have made us a recognized leader in the rodding and racing industries.
