Originally Posted by Wikipedia

The Tremec TR-6060 six-speed manual transmission features six forward speeds and one reverse speed. It is derived from the Tremec T-56 6-speed manual transmission. The forward helical cut gears are synchronized while the reverse gear operates through a fully-synchronized constant-mesh system. The TR-6060 sports removable wear pads on the shift forks, and uses aluminum alloys for the main case, extension housing, and clutch housing. It is manufactured by Transmission Technologies Corporation and is rated for 600 ft-lb of torque.

Originally Posted by Mustang Magazine

So you might be wondering exactly how a Tremec TR-6060 compares with the T56 you know and love. In short, it’s better in just about every way. It can handle more torque thanks to a move from a 10-spline input shaft to a 26-spline unit. Moreover, the new case is stronger, the countershafts are one-piece units, and the gear faces are wider. All these changes add up to much greater strength, which we’ll all appreciate after we start modding these cars. What we noticed while driving the car, however, was its easy, precise shifting despite the factory shifter.

The prime movers in the better shifting are increased synchronizers on all the gears. Where the Terminator T56 had only two synchros on the 1-2 and 3-4 shifts and single synchros on the remaining gears, the TR-6060 offers triple synchros on the 1-2 and 3-4, and dual synchros on all remaining gears, including Reverse. Plus, the synchronizers have been upgraded from a carbon-particle paper to a sintered-bronze material.

Gt500 Transmission Gears
A larger input shaft, beefier gears, more synchronizers, closer gear ratios, and more make this six-speed one that should become a popular aftermarket upgrade.
So this transmission shifts easier, but it also offers a shorter shift throw. "The synchronizer hubs are much narrower, reducing fore and aft shift travel,” Tremec’s Jim Averill explained. “Additionally, the hub system uses three encapsulated ball-and-coil-spring struts that are much more precise than the old-style hoop-and-stamped strut. This also adds to a smoother fore, aft shift.”

So the TR-6060 is smoother, stronger, and just better than its predecessors. That’s cool, but the better news for those who aren’t buying GT 500s is that Tremec will be rolling a lot of this technology into its aftermarket transmissions, so you’ll be able to put all the good stuff in your Mustang soon.

Originally Posted by USAF_RT

but for us SC300 folk and other 2JZGTE people looking for a good 5 or 6spd manual transmission that requires a custom driveshaft anyways, I figured there might be other options out there.

Originally Posted by Arizona

...Stop looking for the easy way out. If the W58 is too weak for you, there is of course the r154(cheap and it fits) Or save you pennies for the V160 swap. Both Toyota and no need to modify...