Modern Overdrive Transmissions for Muscle Cars & Customs

Request a Quote
Items: 0
Total: $0.00

5-speed vs. 6-speed. Which transmission is right for you?

TKO 5-speed Magnum 6-speed

5-speed or 6-speed, Which one is right for me?

Most of our customers understand the value of a strong, durable overdrive transmission as a key to the overall enjoyment of their classic car.  All of our top quality TREMEC gearboxes provide:


  • Quiet highway cruising,
  • Top shelf miles per gallon
  • The ability to handle engines from mild to maniacal. 
  • Thirty years of performance history
  • OE quality and testing on every unit


So which one should you go for, a 5-speed or a 6-speed?


Let’s start with the 5-speed:  Our primary 5-speed offering is the legendary TREMEC TKO.  These gearboxes withstand over 600ft-lbs of constant torque load and can be made to fit most classic cars with little or no modification.  If you have less than 650ft-lbs, want to minimize mods to your car and are going to keep your shifts under 6400rpm, then the 5-speed is the most economical choice. 

Here are a few reasons our customers love their ProFit TKO 5-Speed Systems:

  • Ease of installation – fit most cars with little or no modification
  • Compatibility – fits many OE bell housings and more OE chassis
  • Cost of Entry – the 5-speed is a lower cost option
  • Strength – 600ft-lb constant load rated with Xtreme upgrade options to 950ft-lbs.
  • Workhorse durability – the TKO has been the cornerstone of our business since our founding and has withstood the abuse of thousands of enthusiasts.  A tried and true solution.
  • Wider application – More ProFit kits for more models
  • Dual Speedometer output, easy wire-up, compatible with most mechanical linkage.


Stepping up to a 6-speed:  The Magnum grew out of the program to replace the T56 6-Speed when the new Challenger, GT500, Camaro, Corvette and others grew too powerful and heavy for the T56 architecture.  The Magnum has literally thousands of engineering advances when compared to the T56.  Some of the most important include wider gears with laser cut and welded triple-cone synchronizers, steel shift forks, a TKO style multiple configuration shift rail, dual speedometer output and more.  With 700ft-lbs of capacity and 7000rpm shift capability for less than three grand there is no question that the Magnum is the most bang for the buck in the manual transmission world.  Here are some reasons our customers step up to a ProFit Magnum 6-speed System:

  • Wow Factor – there is just something appealing about more gears
  • Double Overdrive – fifth gear provides a good around town cruising gear while 6th gear really lets you get out on the highway and roll
  • Higher RPM Capability – The Magnum is capable of shifting comfortably at well above 7000rpm.  The TKO is synchronized to about 6500rpm.
  • Higher Torque Capacity – 700ft-lb constant load rating out of the box with Xtreme upgrades to 1100ft-lbs.


Either way you go, you will get legendary TREMEC quality combined with the application specific technology that American Powertrain brings to every project.  Our 5 and 6-speed kits include everything you need to complete your installation, created here at American Powertrain and engineered to the same high standards as your TREMEC transmission.  We back everything with our 2-year comprehensive warranty and our industry exclusive Customer First 24-hour technical support.


Click on the system you think you would like for your car, and if you can’t decide on your own, call us today at 931.646.4836 ext 201 to speak to one of our transmission nuts or click here to request a call from our professional staff.  Our only aim is to help you meet your project goals.

24/7 Help Center

Safe & Secure Shopping
WSM SSL Comodo Secure Site