If you have been in the automotive hobby for even five minutes, you have heard of the TREMEC T-56 6-speed. You have also likely heard of TREMEC’s Magnum 6-speed. What you may not realize is just how different these two transmissions are. A T-56 is not the same as a Magnum, in fact, other than being about the same size and having six forward gears and two overdrives, the two are not the same at all. TREMECs Magnum is the aftermarket version of the OEM TR-6060 6-speed, which is the successor to the original OEM T-56 6-speed.
TREMEC T-56
This is an original TREMEC T-56 six-speed from a Chevrolet Camaro with a Gen-II LT1 (1993-1997). In order to use this in a swap, it needs to be modified.
Photo: Jefferson Bryant
The first TREMEC T-56 came out in 1992 in the Dodge Viper, and was built by Borg-Warner. In 1996, TREMEC purchased Borg-Warner’s North American manual transmission division, with the dominant models made at the time being the T-5 five-speed and T-56. The first T-56 had a power rating of only 330 lb-ft of torque, a power level that a turbo 4-cylinder can best today, but 30 years ago, it got the job done. Over the next 16 years, the power handling increased to as high as 550 lb-ft, with the average OEM-installed T-56 transmission handling between 350 and 450 lb-ft of torque.
Most domestic high-performance models in the era had a T-56 option, including the Chevrolet Camaro, Pontiac Firebird, Chevrolet Corvette, Ford Mustang, Dodge Viper, and a few Dodge trucks. This is where the T-56 swap was born: as these vehicles were wrecked or otherwise damaged and found their way to the salvage yards, the six-speed swap quickly became a go-to proposition for hot-rodders. There are multiple variants to the T-56, however, which meant you really need to do some homework on what will fit your application. An LS-based T-56 is not going to bolt right up to a Ford 302 or Chrysler Hemi, and vice-versa. The LS engine platform is by far the most popular swap option, and you need an LS-based T-56 to use behind one. Otherwise, the input shaft is the wrong length, leaving you to either run a specialty bellhousing or swap the input shaft. The issue with input shafts is that the LS input shaft is no longer made, and they are very hard to find.
The Gen II LT1 input shaft (left) is too short for an LS-based install. Swapping input shafts is not difficult but does require some careful measurements for shimming. The LS-based input shaft is on the right.
Photo: Jefferson Bryant
The gear sets also range in various applications, with wide- and close-ratios, along with multiple overdrive ratios, with some as high as .5:1 in 6th gear. You can verify the gearing and original application on an original T-56 by checking the ID number on the tag.
The biggest concern with swapping OE T-56 units are the variances in shifter placements, speedometer outputs, gearing, and input shaft lengths. While the original T-56 swap is still viable, a new Magnum transmission offers a lot of benefits.
TREMEC Magnum
Here is a new TREMEC Magnum six-speed. This one went into a 1987 Camaro behind a GM Gen-V L83. The shifter position perfectly aligned with the factory console opening, but the tunnel did require some modifications to fit.
Photo: Jefferson Bryant
The TREMEC Magnum 6-speed, while often referred to as the “T-56 Magnum”, it is actually the aftermarket version of the successor to the T-56, the TR-6060. TREMEC originally called the Magnum the T-56 Magnum for marketing purposes, as the T-56 was well known and they wanted to capitalize on the name recognition, whereas the TR-6060 was too new. Developed for the 2007 Ford Mustang Shelby GT500, this six-speed has many upgrades over the original T-56. While the OEM TR-6060 torque rating ranges from 430 lb-ft to 650 lb-ft, the Magnum takes it up to 700 lb-ft of torque handling. While the OEM variants come in multiple shift positions, speedometer ports, and gearing, the Magnum 6-speed was designed for the aftermarket, so the options are simplified. Unlike the TR-6060, the Magnum uses a removable bellhousing with two input shaft lengths: GM (LS-based) and Ford (Modular-based).
Gearing is also simplified with two sets:
All Magnums use a 26-spline input shaft and 31-spline output and have both mechanical and electronic speedometer outputs. The GM version is designed for a hydraulic clutch release, while the Ford version uses a mechanical release bearing. There are three unique shifter positions, with more options available with aftermarket shifter adapters, allowing you to fit the Magnum into many different applications.
Upgrades Over The T-56
Each Magnum has two speedometer outputs positions, a mechanical unit and an electronic sending unit.
Photo: Jefferson Bryant
The TR-6060 and Magnum are much stronger than the T-56 due to major upgrades internally. The synchros are narrower to provide more space between the speed gears, which are now 2-piece laser-welded gears that require less machine work, allowing the teeth to be tighter spaced. This increases the face width of the gears, yielding higher torque capacity.
In a manual transmission, the synchros are critical to smooth operation. The T-56 used a 3-key retainer, which worked, but is prone to movement. The Magnum synchros are narrower but use a triple-cone design that increases the overall diameter and surface area, where the T-56 uses mostly double-cone for 1st and 2nd, and single cone for the rest.
GM Magnums use hydraulic release bearings like this Hydramax shown here, whereas Ford-spec models use manual release bearings.
Photo: Jefferson Bryant
The shift forks in the T-56 are aluminum, which had a bad habit of bending. The issue is the T-56 forks use a separate keyway for the z-bar shift link. For the Magnum, the forks have a cast-in Z-link that stabilizes the fork so they can remain light and strong. Additional upgrades include larger bearing surfaces and the 26-spline input shaft.
The T-56 made the 6-speed swap the most popular manual conversion in the industry, they were readily available and easy to swap. As horsepower levels have increased significantly in the last 20 years, the need for a bigger, badder 6-speed became clear. TREMEC’s Magnum six-speed is the go-to manual for any hot rod, muscle car, truck, or tuner you can think of. Taking things a step further, TREMEC now has the Magnum F and Magnum XL versions which are the same internally, but are longer than the Magnum. The Magnum measures 26.6” from the input shaft to the center of the shifter, Magnum F is the goldilocks unit at 29.4” (Interestingly, the Magnum F is 2 inches shorter overall due to a shorter tailshaft), and the Magnum XL measures 34.9”. Check out the Magnum 6-speed offerings at TREMEC.com to determine which model best fits your application.
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