Tremec’s new TKX 5-speed has already made a name for itself as being an outright upgrade over its predecessor, the TKO. However, few suppliers have taken the time to sit down and go through the actual differences until American Powertrain (AP) recently picked both apart in the quintessential side-by-side comparison.

“When Tremec designed the TKX they wanted a new design just for the aftermarket. In the past the aftermarket transmissions were based on OEM designs in house,” AP explains.

The complete revamp touched on everything from case shape to gear loading. Squared-off shoulders made the TKO a tight fit in many transmission tunnels. “One of the reasons the TKO was a boxy shape was that it was a ‘topload’ design, meaning the gears came in from the top.”

Tremec slimmed the TKX silhouette by making its gearset an end-load instead of topload. The design is actually similar to that of the Magnum 6-speed and is inherently stronger than the top-down approach. Multi-cone synchronizers also come from the Magnum and offer 7,500 RPM shifting capabilities.

Luckily, the TKX is similar to the TKO in all the right places for those looking to do a one-for-one upgrade. Similarities include overall length, output shaft size, bellhousing bolt pattern, throwout bearing, and input shaft size. TKO crossmembers and driveshafts are a direct fit for TKX swaps. American Powertrain is clearly an authority when it comes to adding aftermarket gears and all it takes is a quote request to get going on your overdrive excursion.