What Is The Difference Between The TREMEC Manual Transmissions?

Question: I am looking for a manual transmission for my 1972 Chevelle Wagon, and I am not sure which one I should go with. What is the difference between the T56, Magnum, F, XL, and TKX?

– Marty, Garden Grove, CA

Answer: That’s a great question, Marty, one that comes up all the time. The classic TREMEC T56 6-speed has been a mainstay in the hot-rodding world since its introduction in the 1992 Dodge Viper. Since then, TREMEC 6-speeds have been the go-to manual transmission for Vipers, Corvettes, Mustangs, Cadillacs, and even the Aston Martin DB7 and Vanquish, so it is a shoe-in for your muscle car, truck, or whatever you want to row gears in. There are several different versions of the TREMEC 6-speed, so let’s break them down for you so you can make an informed decision.

Dodge Viper RT/10

The original T56 in the ’92 Viper was rated for 330 lb-ft of torque, but most of the later units were good for 350-450 lb-ft of torque. This would cover most factory-installed T56 models up to 2006. The TR-6060 replaced the T56 in 2007. While the original T56 is a great transmission, the newer models can handle more power.

Tremec Magnum

Photo: TREMEC

MAGNUM: The “kingpin” of the line is the Magnum dual-overdrive 6-speed. The Magnum was developed by TREMEC with modern OEM technology to deliver crisp shifts while managing up to 700 lb-ft of torque. The Magnum is the aftermarket version of the TR-6060 OEM 6-speed used in the Viper, Mustang, and Camaro. There are major differences, however, as the Magnum features a removable bellhousing, multiple shifter locations, dual speedometer outputs (mechanical and electronic), and comes in either close- or wide-ratio gearing with two different overdrive options, so you can order the trans gearing that best suits your needs.

Tremec Magnum F

Photo: TREMEC

MAGNUM F: As the original T56 units are becoming incredibly hard to find, TREMEC launched the Magnum F as a replacement for GM’s 98-02 F-body platform. This is a modified Magnum 6-speed that specifically fits the Camaro/Firebird with an LS engine. It uses the F-body shifter location, which is in the middle between the Magnum (too far forward) and Magnum XL (too far back), so the F is the Goldilocks of 6-speeds for many swap platforms, including A80 Supras, FD RX-7s, and others that need a mid-length shifter position. The transmission itself is beefed up over the original T56 with double and triple cone synchros, wide-faced gears, optional cooling ports, and it carries the same 700 lb-ft torque rating as the Magnum.

Tremec Magnum XL

Photo: TREMEC

MAGNUM XL: When you need the deep reach, go for the XL. A slimmed-down version of the Magnum, the XL has all the strength and OE durability of the original Magnum, but with less bells and whistles. The Magnum XL has one shift position located at the very back of the extended tail housing for long-reach applications such as the S197 Mustang (this model’s original application). It has one electronic speedo port, no mechanical speedo option. It does come with a steel SFI-approved bellhousing, transmission mount, and a TREMEC shift ball. The Magnum XL is designed to use the OEM hydraulic clutch release, which means parts are readily available without needing specialty pieces. Common late-model fitments are 2005-up Mustang and the GM version of the Magnum XL will fit the 2003-up Pontiac GTO, Cadillac CTS-V, and fifth-gen Chevrolet Camaro.

Tremec TKX

Photo: TREMEC

TKX: Want a manual but need to save space? The TKX is the first TREMEC transmission developed exclusively for the aftermarket. TREMEC took the best parts of their OE platforms and utilized them in a blank-sheet design. Unlike the large-case Magnum series, the TKX is about the same size as a TKO, but with a 600 lb-ft torque rating, an RPM limit of 8,000 and the ability to be shifted at 7,500 RPM, the TKX is ready for war. With three shifter locations, the TKX fits under most transmission tunnels with little-to-no modification. All case seams are gasketed for leak-free operation, and the shifts are smooth due to the sintered-bronze and carbon multi-cone synchros and rings. The TKX comes in specific GM and Ford variations to accommodate engine platforms and transmission mounts. There are four Ford gear ratios and three GM gear sets, with overdrives ranging from .68 to .81, so you can select the right gearing for your street rod, truck, autocross, or road racer.

The TREMEC Magnum and its variants are the kings of manual transmissions, with an option for just about any application. If you don’t need that second overdrive or the additional 100 lb-ft of torque capacity, the TKX 5-speed fits in just about any transmission tunnel and delivers crisp shifts at high RPM for high-revving, gear-banging fun. For your specific application, the TREMEC TKX is the best option as there are no tunnel mods, and you can reuse the stock crossmember. In fact, the TKX was originally developed using a 1970 Chevelle as the base vehicle for fitment.