Shift Lever
Converting from an automated to a manual transmission in your heavy-duty truck removes the factory electronic shifter, leaving no linkage from the cab to the new Fuller gearbox—making a complete shift lever assembly essential for reliable, driver-controlled shifting. Kustom Truck Parts offers shift lever & upfit kits tailored for Kenworth and Peterbilt chassis, with options for big block (14+ liter, e.g., Cat C15/3406E, Cummins ISX) and mid block (10-13 liter) engine applications.
Our transmission shift kits include:
*Shift Lever Kits — Cab-side assembly including the shift lever, boot, retainer, and floor plate/cover components.
*Transmission-Specific Upfit Kits (sold separately) — Gearbox-side components that pair perfectly with the shift lever kit to provide everything needed from the shift tower through the shift knob, including the shift tower, knob, medallion, isolator bushings, airlines, and fittings.
By offering the shift lever kit and transmission upfit kit separately, customers can purchase only what's required for their specific build—whether replacing a damaged cab-side lever, upgrading to a new transmission configuration, or completing a full manual conversion. When used together, the two kits create a seamless, full-shift assembly with precise feel and durability.
Upfit kits support common Fuller configurations:
- 8LL (RTO/RTX 9 Series)
- 10-speed
- 13-speed
- 18-speed
These kits ensure smooth, reliable shifting, reduced transmission wear, and factory-like control—ideal for transmission conversion projects.
Browse below for your chassis, engine size, and transmission match. Pair with our clutch linkage kits for a complete manual drivetrain conversion. Need help determining which kit (or combination) fits your Fuller model or hood configuration? Contact our team for expert guidance on your build.
