GKB 

At GKB, that connection began with a question:

Could the most powerful Mercedes-Benz engine of its era—the M120 V12—be fitted into the classic C126 SEC chassis? And beyond that, could it be paired with a 6-speed manual transmission?

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We didn’t just ask the question—we answered it.
By replacing the factory 4-speed automatic with a 6-speed manual and mating it to the M120 V12, we reimagined what a classic Mercedes-Benz could be. The result? A visceral, analog driving experience that turns every shift into a statement.

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That first build changed everything.

Today, GKB specializes in manual transmission conversions for the W140, C140, R129, and C126 chassis—swapping their original automatic gearboxes for a 6-speed manual, all powered by the iconic M120 V12. We believe these chassis, produced from 1980 to 2002, represent the most versatile platform in Mercedes-Benz history. With the right transmission and engine, they become something else entirely: raw, deliberate, and unmistakably Mercedes-Benz.
 

These aren't engine swaps. 
They’re purpose-built machines—crafted to bring the driver closer to the road, the machine, and the soul of performance.
 

This is GKB.