Tremec TKX, TKO & T56 Swap Guide | Clutches, Mounts, Bellhousings & More

Tremec has become synonymous with aftermarket manual transmissions. They offer a variety of transmissions for everything from lightweight nostalgia hot rods, high-powered muscle cars, and off-road trucks. They also happen to be a great complement to modern engine swaps. But Tremec’s long history as both a supplier to the OE’s and the aftermarket means there are so many options that it can be hard to figure out which one is right for your project. Consider this article a quick overview to help you select your Goldilocks gearbox and figure out what you’ll need to install it.

Before we get into the specifics of each Tremec transmission from a functional standpoint, let’s talk about a few of the big differences between the aftermarket Tremec 5- and 6-speed transmission designs that will matter when weighing your 5-speed vs 6-speed manual transmission options. Generally speaking, 5-speed designs like TXO and TKX are dimensionally smaller, making them easier to fit under a transmission tunnel that once covered a smaller old-school 3 or 4-speed. 6-speeds are bigger in pretty much every dimension and may require more invasive sheet metal and crossmember surgery.

Also note that most of the 5-speeds are available with familiar bolt patterns and input shaft dimensions. Those trusty old bolt patterns that you’ve been seeing on Muncies and Ford Toploaders since the dawn of time are still available on TKO’s and TKX’s. This means that sometimes an original bellhousing can be retained when the transmission is upgraded. On the other hand, the T-56 derived 6-speeds carry the T-56 bolt pattern, which is familiar to folks accustomed to working with these transmissions, but it’s unlike anything you’ll find on an old-school manual.

While we’re comparing the dimensional aspects of modern Tremecs with older manuals like Muncies and Saginaws, it’s worth noting one of Tremec’s major advantages. Transmissions with traditional external linkage and shifters are famously finnicky to set up and keep that way. Not only that, but packaging that external stuff can be tricky in the tight confines of a hot rod or classic car tunnel. Both Tremec 5- and 6-speed designs use integrated shifters with internal shift rails that are both compact and precise. On top of that, Tremecs meant for the aftermarket also typically feature multiple shifter locations to maximize compatibility in a huge variety of swap combinations.

What is The Difference Between T56 VS T56 Magnum?

The short version of the story is that the Magnum is Tremec’s 6-speed for the aftermarket and functionally it’s a more versatile, beefed-up version of the stock T-56. Magnums boast a hefty 700 lb-ft. rated torque capacity thanks to some internal upgrades. Magnums have better synchros and stronger shift forks with cast in keys for more positive shifts. A stronger input shaft, stronger one-piece countershaft, and speed gears with larger face widths contribute to the uprated torque capacity. They look similar from the outside, but there’s a lot hiding inside a Magnum that makes it a much stronger ‘box.

Knowing that Magnums were bound for any number of unconventional swaps, Tremec also added multiple T-56 Magnum shifter locations for a total of three possible placements. We’ve found this to be incredibly handy, allowing us to put the shift lever where it belongs in a variety of cars and trucks. There’s also a Tremec T-56 Magnum-F and Tremec T56 Magnum-XL designed specifically for GM F-bodies and late model Mustangs, respectively. While the latter two are application specific, they can be used in other swaps for even more latitude regarding the shifter location.

Tremec TR-6060

The TR-6060 is yet another Tremec 6-speed design. You can find these in factory hot rods like the Chevy Camaro and Dodge Challenger, and therein lies the critical difference between the TR-6060 and the Magnum. The TR-6060 was designed specifically for these OE applications, while the Magnum was designed for the aftermarket, making it a more versatile transmission.

Most TR-6060’s have an integrated bellhousing, specific to whatever its OE application was. The Magnum is designed to use a separate bellhousing, allowing it to be adapted to just about anything. The shifter location is also different. If you’ve ever uncovered a TR-6060 in the junkyard, you’ve likely noticed the oddball semi-remote shifter unit with the u-joint on it. Most TR-6060’s have a shifter that mounts to both the transmission and the car body. The three possible shifter locations on the top of a Magnum make it much more versatile in this respect as well.

Tremec TKO 500 & TKO 600 Transmission

For years, the Tremec TKO 5-speed was the workhorse for the aftermarket. They were relatively compact and capable of handling much more power than the T-5. Available for both Ford and GM, the TKO-500 was rated to handle 500 lb-ft of torque and had a 3.27 first gear and .68 overdriven fifth. Ford and GM TKO-600’s were rated to 600 lb-ft. and were available with a 2.87 first and either a .82 or .64 overdrive. We’ve dropped TKOs in several projects and found them to be smooth shifting and reliable when treated responsibly. We’ve also pushed them to their limits by exceeding the rated torque capacity, with mixed results.

TKOs were toploaders, necessitating some relatively tall box shapes on top of the case. When swapping these transmissions into 60’s and 70’s classics, we found that these areas were almost always in contact with the tunnel and required cutting or reshaping of the sheet metal.

Tremec TKX VS TKO

The popularity of TKOs swapped into the old hot rods, muscle cars, and classic trucks that we all love led Tremec to develop a successor that answered some of the specific requirements for these applications. Instead of being derived from an OE transmission, this new transmission would be a clean-sheet design with classic car swaps in mind. With the introduction of the TKX, Tremec has discontinued the old TKO 5-speeds.

To solve some of the problems with the old TKOs, the design of the Tremec TKX 5-speed manual transmission is completely new. Instead of dropping the gears in from the top, TKX’s load from the rear. This may not seem significant, but it allows a more compact case better suited to packaging in older cars. Internally, TKX 5-speeds use an improved three-piece synchro set instead of the old brass rings of the TKO as well as shift rails that are supported by bearings instead of O-rings. TKO’s were famous for shifting issues above 6,000 rpm and these improvements to the TKX were designed to alleviate that frustration, allowing for shifts up to around 7,500 rpm depending on the mass of the clutch and flywheel. Like the TKO, the Tremec TKX shifter location can be adjusted by rotating the shifter plate or adding a mid-shift TKX shifter relocation kit for a third location. Tremec TKX gear ratios vary, with different models carrying either a 3.27 or 2.87 first gear and fifth gear overdrive ratios of .81, .72, or .68. Use our handy gear ratio calculator to figure out what’s best for your combination.

Here at Speedway Motors, we’ve used lots of Tremec TKO and TKX transmissions in our own project cars, so we’ve got quite a bit of experience with both 5-speed options. While some may not notice or care about the ability to shift a TKX at 7,500 rpm, this is a noticeable improvement for serious cars that are spending time on the track. The lower profile of the TKX case is a huge improvement that everyone will notice. We’ve spent some serious time cutting and bashing stock muscle car and truck tunnels to make room for the box-shaped goomises on top of the TKO. The profile of the TKX, on the other hand, is not much different than an old Muncie or TH350, making it much easier to fit in an old car without performing any surgery. We just completed a Tremec TKX install in a C10 pickup without cutting the tunnel, a feat that would have been impossible with a TKO. They haven’t been on the market for as long as the old TKOs, but so far our Tremec TKX reviews are glowing.

Tremec TR-4050 Transmission

Put simply, the TR-4050 is Tremec’s truck transmission. They are the go to Tremec 4x4 transmission, but are available configured for both 2- and 4-wheel drive. They have a deep 6.16 first gear in addition to an 0.76 overdrive and are rated to handle 600 lb-ft. of torque. The Tremec TR-4050 is built to be a workhorse transmission while still having much more modern shifting manners when compared to old granny-geared 4-speeds and even to more modern truck boxes like the NV4500.

What is The Difference Between Tremec 3650 And T5?

The T-5 transmission is a legend, largely for its longevity and the wide range of cars and trucks that left the factory with one. The T-5 first hit the streets in 1980 AMCs, of all things, but they entered the collective consciousness of the hot rod world when they showed up in Fox-body Mustangs and Camaros. Because of their compact size, smooth shifting, overdriven 5th gear, and huge production numbers, T-5 transmissions became common swaps in street rods and classics.

Remember that acquisition of BorgWarner’s manual transmission business by Tremec? Well in addition to the T-56, Tremec also took over the rights to build the T-5. They’re still available new, and Speedway Motors sells the Ford version of the Tremec T-5, often as part of a kit to adapt the trusty little 5-speed behind flathead V8’s. They’re compact and lightweight, making them perfect for hot rods where space is tight. Their 300 lb-ft. torque rating somewhat limits them to flatheads and small blocks, but they’re still a viable option for hot rodders looking for an overdrive manual and their ubiquity has led to the availability of plenty of Tremec T5 parts.

The TR3650 has very little in common with the T-5 other than both having been the original equipment 5-speed in Ford Mustangs, albeit in different eras. In 1996, the T-45 replaced the T-5 in factory Mustangs. It was an end-loaded design instead of a top-loader like the T-5 and borrowed the larger synchros from the T-56. Torque handling was improved slightly over the T-5 and this design lived in Mustangs until 2001 when it was replaced by the next evolution of Tremec Mustang manual, the TR3650. These are end-loaded like the T-45 and carry a 360 lb-ft. rating. Like the TR-6060, swappers will find the integrated bellhousing to be a limiting factor and a new TKX will make more sense for most applications.

To facilitate the ever-popular LS engine manual transmission swap, Speedway Motors offers a Tremec TKX LS kit to back that 5.3, LS1, 6.0, etc. with a TKX. There’s also a Tremec Magnum kit for LS swappers looking for more gears and bigger power handling. These kits are packaged with a bellhousing, clutch and flywheel, and a hydraulic throwout bearing. Even the required bolts and wiring harness plugs are included.

Since the whole world doesn’t want an LS swap, there are also old school Chevy Tremec 5-speed options like the Tremec for 350 small block kit that will work with the old school mouse motors as well as some big blocks (as long as you mind the maximum torque capacity). Later engines can use the [86-up Chevy TKX kit]. Those looking for more gear or with bigger power Chevy engines can opt for a T-56 Magnum kit for 85-earlier Chevy engines or a Tremec Magnum Kit for ’86-up Chevy.

Tremecs are commonly associated with Ford cars, and some Ford fans will opt for the OE applications that were originally designed to bolt up to Ford engines. OE Tremecs are often not strong enough for serious power, so with those applications in mind there’s also a TKX kit for Ford fans wanting to back their 289, 302, or 351W small blocks with a stout TKX.

These kits are complete, but leave out a few items that will be application specific like a Tremec shifter handle, shift knob, and transmission mount, Also don’t forget that your transmission swap will also likely require a different length driveshaft. Speedway Motors Custom-Length Driveshaft Kits allow you to spec not only the right length, but also a driveshaft that will handle the torque and power that’s spinning it. We’ve had exploded u-joints wipe out the transmission on their way out, so protect your transmission investment and don’t cut corners here.