How to Identify an Eaton Fuller Manual Transmission

Before you buy a manual truck, you should know exactly which transmission is in it. Eaton Fuller makes this easier than most — their model numbers tell you the speed count, ratio type, and features.

Find the Tag

Every Eaton transmission has a metal model tag bolted to the side of the case, usually on the right side near the PTO opening. It lists the model number (e.g., RTLO-18918B) and the serial number.

Decode the Model Number

Eaton's naming convention breaks down like this:

• R = Roadranger
• T = Transmission
• L = Low-noise (or F for fuel economy series)
• O = Overdrive top gear
• 18 = Number of forward speeds
• 918 = Ratio code / series
• B = Suffix (feature variant)

So RTLO-18918B is an 18-speed Roadranger with overdrive. An RTLO-13708B would be a 13-speed.

Count the Shift Positions

If the tag is missing or painted over, count the shift positions:

• 9-speed: Low, 1–4 in low range, flip the switch, 1–4 in high range (with one position reused)
• 10-speed: Low, 1–4 low range, flip, 1–4 high range, plus a splitter
• 13-speed: 9-speed base + a splitter on the top 4 gears
• 18-speed: 9-speed base + splitter on every gear (high/low on each)

Look at the Shift Knob

The shift knob is a dead giveaway. An 18-speed has a range switch on the front and a splitter button on the side. A 13-speed has the splitter only on the upper gears. A 10-speed has a range switch but no splitter.

Why It Matters

The transmission affects resale value, rebuild cost, and how the truck drives. An 18-speed commands a premium; a worn 10-speed is a bargaining chip. Always confirm the model number matches what the seller claims — and cross-reference it with the truck's spec sheet.

On 3PedalSemi, every listing shows the transmission and speed count up front.