29 Spline vs. 26 Spline T56 Magnum Input Shafts

29 Spline vs. 26 Spline T56 Magnum Input Shafts

So you’re making enough steam in your stick shift badass to start twistin’ some 26 spline input shaft goodness? Well welcome to the club, now what to do…..

The great brains at G-Force Transmissions have developed a new 29 spline input shaft. Great you say, what will 3 extra splines get me? Well, let’s look at the difference between the 26 spline and the 29 spline:

  • 26 spline: 1.125 inch diameter - strong
  • 29 spline: 1.25 inch diameter - stronger

As of now, I'm only aware that G-Force produces these. Currently, they manufacture the 29 spline for the LS T-56 Magnum, as it's the most popular. They're planning to introduce the Ford and Challenger/Hellcat options next, as they rank as the second most popular choices.

The cost is $625, and you'll additionally require the bearing, priced at $45, and the race, costing $23. The good news is it uses the same seal for this shaft as the 26 spline. You'll also need a professional to install this in your transmission if you're unable to do it yourself. Keep in mind that these won't work with a stock gearset; you must have the upgraded, and better, G-Force gearset. 

Other parts to consider when making this change include your current throw-out bearing program. For my setup, I use a Tilton 6000 series hydraulic release bearing. They manufacture many different varieties for various applications. The ID of this assembly is 1.40”, providing ample room for the 29 spline shaft – fortunate indeed!

Now, there's the matter of clutch discs. The 29 spline shaft is relatively new, so there isn't a vast selection of disc suppliers. I've learned that Boninfante is making these available. I have some on order from Ace Manufacturing as they're my preferred source for 5135 discs, but I'm still waiting for them to arrive.