The Tremec T-56 Magnum is the most popular aftermarket six-speed manual transmission for V8 performance builds. It handles 700 lb-ft of torque, weighs 135 lbs dry, and fits behind virtually any LS, LT or Ford modular engine with the right bellhousing. But choosing the correct version is where most builders get stuck.

There are over a dozen part numbers in the Magnum range. They differ by input configuration (GM or Ford), gear ratio set (close or wide), overdrive depth (0.50 or 0.63 sixth gear), shifter position, and output spline. Pick the wrong one and you'll end up with a gearbox that cruises at uncomfortable RPM, doesn't clear your tunnel, or needs an adapter you didn't budget for.

This guide covers every current variant, explains the trade-offs between them, and helps you match the right Magnum to your build - whether it's an LS-swapped classic, a kit car, a track weapon or a motorway cruiser.

What the T-56 Magnum Actually Is

Despite the name, the T-56 Magnum isn't a T-56. It's an aftermarket version of the TR-6060 - the OE transmission found in factory Camaros, Challengers, Vipers and GT500s from 2007 onwards. Tremec used "T-56" in the name to signal compatibility with existing bellhousings and aftermarket support, and "Magnum" to indicate the step up in capability.

Compared to the original T-56 (which was rated at around 450 lb-ft), the Magnum has wider gear faces, a stronger one-piece countershaft, redesigned two-piece speed gears with laser-welded clutching rings, and a completely new synchroniser design using spring-loaded ball-type detents instead of the old hoop-and-key system. The result is substantially more torque capacity and noticeably better shift feel.

The key advantage for builders is that the Magnum uses a separate bellhousing rather than the integrated bell found on OE TR-6060s. This means you can bolt on an SFI-certified bellhousing to match your engine - LS, LT, small block Chevy, big block Chevy, Ford modular, Ford Windsor, and more.

GM Input vs Ford Input

Every Magnum is built in either a GM or Ford input configuration. This determines the input shaft spline count, the front face bolt pattern, and which bellhousings and clutch systems will work.

GM-Style Magnum

Modelled after the 1998–2002 F-body (Camaro/Firebird) T-56. Uses a 26-spline input shaft and accepts any bellhousing designed for the GM T-56 pattern. This is the most common choice for LS and LT swaps because the bellhousing and clutch ecosystem is enormous. If you're putting an LS into a classic British car, a Defender, a Cobra replica or any custom chassis, this is almost certainly the one you want.

Ford-Style Magnum

Modelled after the 2003–2004 Terminator Cobra T-56. Uses a 26-spline input shaft sized for Ford applications and accepts Ford-pattern bellhousings. The right choice for builds using Ford modular (4.6L, 5.0L Coyote) or Windsor engines where you want to retain Ford clutch hardware.

Important: The input configuration is about the engine side of the transmission, not the vehicle it's going into. An LS engine going into a Ford Mustang still uses a GM-style Magnum with a GM-pattern bellhousing, because the bellhousing matches the engine block, not the car.

Close Ratio vs Wide Ratio

This is the decision that affects how the gearbox actually feels on the road or track. Tremec offers two fundamental gear set families, each with variations in the overdrive gears.

Close Ratio (2.66 First)

Gear	Ratio
1st	2.66
2nd	1.78
3rd	1.30
4th	1.00
5th	0.80
6th	0.63 or 0.50

The close ratio set has a shorter first gear and tighter spacing through the middle of the range. The gaps between gears are smaller, which means less RPM drop on each upshift. This keeps the engine in its powerband more consistently - exactly what you want on track, in autocross, or in any situation where you're using the gearbox aggressively.

The trade-off is that first gear is shorter, which can make low-speed manoeuvring in traffic feel a bit busy, and the tighter spacing means the overall spread from first to sixth is narrower.

Wide Ratio (2.97 First)

Gear	Ratio
1st	2.97
2nd	2.10
3rd	1.46
4th	1.00
5th	0.80 or 0.74
6th	0.63 or 0.50

The wide ratio set has a deeper first gear and bigger steps between ratios. This gives you more mechanical advantage off the line and a broader overall spread. The wider gaps mean more RPM drop per shift, which is less ideal for sustained high-RPM track driving but perfectly fine for road use.

Where the wide ratio really wins is flexibility. The combination of a deep first gear for pulling away and a deep overdrive sixth for motorway cruising gives you a gearbox that works well across a huge range of driving conditions. For road-going builds, restomods, tourers and daily drivers, this is typically the better choice.

Which Should You Choose?

Choose close ratio if: you're building primarily for track use, autocross, spirited B-road driving, or you're running a relatively short diff ratio (3.90+) where you want the tighter spacing to keep gear speeds close together.

Choose wide ratio if: you're building a road car, a tourer, a restomod, or anything that needs to be comfortable at motorway speeds. Especially relevant in the UK where a quiet 70 mph cruise matters. Also suits builds with moderate diff ratios (3.42–3.73) where the wider spread gives you the best of both worlds.

The Sixth Gear Decision: 0.63 vs 0.50 Overdrive

Regardless of whether you go close or wide in the lower gears, you then need to choose your overdrive depth. This is the ratio that determines your cruising RPM and has a bigger impact on daily liveability than most people expect.

0.63 Sixth Gear

A moderate overdrive. Cruising RPM at 70 mph will be higher than with the 0.50, but the step from fifth to sixth is smaller, so the transition feels natural. Better for track-oriented builds where you want sixth gear to still be a usable performance ratio rather than a pure economy gear. Also a safer choice if you're running a very tall diff ratio (3.08–3.42) where a deeper overdrive would drop RPM too low.

0.50 Sixth Gear

A deep overdrive. This drops cruising RPM significantly - typically into the 1,600–1,800 RPM range at 70 mph depending on your diff and tyre combination. Ideal for road cars, tourers and motorway builds where you want the engine loafing along quietly. The trade-off is a larger RPM drop from fifth to sixth, which can feel like the engine "falls off" on aggressive upshifts.

Use our Gearbox Ratio Calculator to model the exact cruising RPM for your specific tyre size and diff ratio - it has presets for every Magnum variant so you can compare them side by side.

Magnum vs Magnum-F vs Magnum XL

Beyond the gear ratios, Tremec makes three chassis variants of the Magnum. They share the same internals and torque capacity but differ in external dimensions and shifter location.

T-56 Magnum (Standard)

The universal version. Three possible shifter positions along the top of the tailhousing, plus a mid-shift (forward) position. Dual speedometer pickups - mechanical and electronic - for maximum compatibility with both classic and modern gauge setups. This is the most versatile version and the default choice for custom builds, kit cars and any application where you need to position the shifter precisely.

T-56 Magnum-F

Designed as a direct replacement for the factory T-56 in 1998–2002 Camaros and Firebirds. The tailhousing positions the shifter in the stock F-body location, and the overall length matches the original transmission. Only one shifter position. If you're upgrading a fourth-gen F-body from a stock T-56 to a Magnum, this is the clean swap - no tunnel work required.

T-56 Magnum XL

An extended-length version with the shifter positioned further rearward. Originally designed for 2005+ Mustangs as a replacement for the MT82, but also popular for classic car builds where you want the shift lever further back in the cabin. Available in kit form with an SFI bellhousing, crossmember, trans mount and shifter. Uses a direct-mount rigid shifter rather than the semi-remote designs found in some OE applications.

For most custom builds and LS swaps, the standard Magnum is the right starting point. The Magnum-F and XL are purpose-built for specific vehicle platforms.

What Else You Need

The Magnum is a bare transmission. To complete the installation you'll also need:

• Bellhousing - Must match your engine block pattern. QuickTime SFI-certified steel bellhousings are the most popular choice. Lakewood and Chevrolet Performance also offer options for LS, LT and traditional small/big block applications.
• Clutch and flywheel - Matched to the Magnum's 26-spline input shaft. Our Monster Clutch and clutch and flywheel ranges cover everything from mild street setups to 1,000+ hp twin-disc packages.
• Hydraulic release bearing or slave cylinder - The Magnum supports both hydraulic and mechanical clutch actuation. Hydraulic is the modern standard and significantly easier to set up in a custom installation.
• Crossmember and mount - Application-specific. The Magnum XL kits include these; for standard Magnums, you'll need to source or fabricate a crossmember to suit your chassis.
• Driveshaft - The Magnum uses a 31-spline slip yoke output. You'll need a driveshaft cut to length for your specific application, with the correct yoke at the transmission end and the correct flange or yoke at the differential end.
• Speedometer - Electronic VSS output is built in. If you're running a classic mechanical speedo, the mechanical drive is also available. Your gauge setup determines which you need.

We supply full packages that include the transmission, bellhousing, clutch and all installation hardware - get in touch if you want us to spec a complete kit for your build.

Complete Part Number Reference

Here's every current Magnum variant we stock, with the key specifications for each:

Part Number	Type	Input	1st	6th	Shifter Positions
TUET11009	Magnum	GM	2.66	0.63	3
TUET11012	Magnum	GM	2.97	0.50	3
TUET16885	Magnum	GM	2.97	0.63	3
TUET16884	Magnum	Ford	2.97	0.63	3
TUET11010	Magnum	Ford	2.66	0.63	3
TUET16362	Magnum-F	GM	2.66	0.63	1
TUET16363	Magnum-F	GM	2.66	0.63	1
TUET17638	Magnum-F	GM	2.97	0.50	1
TUET11430	Magnum XL	Universal	2.66	0.50	1
TUET11940	Magnum XL	Universal	2.66	0.63	1
TUET16886	Magnum XL	Universal	2.97	0.63	1

All variants are rated to 700 lb-ft torque, weigh approximately 135 lbs dry, use a 26-spline input shaft and 31-spline output, and are max-rated at 7,800 RPM.

Common UK Build Scenarios

LS3 into a Classic British Chassis

GM-style Magnum, wide ratio with 0.50 sixth gear (TUET11012). Pair with a 3.54 or 3.73 diff for relaxed motorway cruising and strong off-the-line performance. A QuickTime LS bellhousing completes the connection. Use our ratio calculator to verify cruising RPM with your specific tyre size.

Cobra Replica or Kit Car

GM-style Magnum, close ratio with 0.63 sixth gear (TUET11009) if the car is track-focused, or wide ratio with 0.50 sixth (TUET11012) if it's a road car. Kit cars are light, so the close ratio set works well even with moderate power. The standard Magnum's three shifter positions give you the flexibility to position the lever exactly where the cockpit needs it.

Defender LS Swap

If you're going manual rather than our complete LS3 + 6L80 conversion kit, the wide ratio Magnum with 0.50 overdrive is the natural choice. Defenders are heavy and often see mixed-use driving - the deep first gear helps with low-speed off-road situations and the deep overdrive keeps motorway RPM civilised.

Track Day Build

GM-style Magnum, close ratio with 0.63 sixth gear (TUET11009). The tight spacing keeps you in the powerband through corners, and the 0.63 sixth is still a usable ratio for the straights. Pair with a 3.73 or 3.90 diff. If you're planning serious track abuse, consider speccing a heavier-duty clutch from the Monster Clutch range to handle repeated hard launches and aggressive shifting.

Model Your Setup Before You Buy

The best way to confirm which Magnum is right for your build is to model the complete driveline. Our Gearbox Ratio Calculator has presets for every Magnum variant - select one, enter your tyre size and diff ratio, and see the exact speed at redline in every gear plus your cruising RPM at any target speed. It takes thirty seconds and could save you from ordering the wrong gearbox.

Open the Gearbox Ratio Calculator →

Need Help Choosing?

If you're not sure which Magnum suits your build, or you need a complete package including bellhousing, clutch, hydraulics and installation hardware, get in touch with our team. We spec transmission packages for LS and LT swaps, kit cars, restomods and custom engineering projects - and we ship across the UK.

Browse the full Tremec range →