24x vs 58x Reluctor Differences for LS and LT

One of the first questions on any LS swap is whether you're dealing with a 24x or 58x engine. It determines what harness you need, what PCM you run, and what will actually work together. Here's what you need to know.

What the Reluctor Wheel Does

The reluctor wheel sits on the crankshaft and works with the crank position sensor to tell the PCM where the engine is in its rotation. The PCM uses this signal to fire the injectors and spark at the right time. Without a clean crank signal, the engine won't run.

The number refers to how many teeth are on the wheel. 24x has 24 teeth. 58x has 58 teeth.

Which Engines Use Which

24x (Gen III) LS1, LS6, LQ4, LQ9, and the 4.8, 5.3, and 6.0 truck engines through 2006. The cam sensor mounts at the rear of the block.

58x (Gen IV) LS2, LS3, LS7, L76, L92, and 2007+ truck engines. The cam sensor mounts up front in the timing cover.

Gen V LT LT engines use a different system altogether. If you're doing an LT swap, you're in a different category and need a harness and ECM set up specifically for Gen V.

The Main Differences

The Wheel Itself

The 24x is a two-piece design. The 58x is one piece. The one-piece design tends to give a cleaner, more accurate signal to the PCM.

Cam Sensor Location

On 24x engines, the cam sensor is in the back of the block where the distributor used to go. On 58x engines, the cam sensor is in the front timing cover. If you're swapping a 58x engine into something, you need the timing cover with the cam sensor provision and the correct cam gear.

PCM Differences

Gen III 24x engines typically run P01 or P59 controllers. Gen IV 58x engines run E38, E67, or similar. They're not interchangeable. The harness, PCM, and engine all need to match.

Throttle Options

This is one worth knowing. With factory GM electronics, 24x engines can run either drive by cable or drive by wire. The 58x engines only work with drive by wire when using OEM controls. If you want a cable throttle with factory PCM, you need a 24x setup.

Transmission Control

On 24x setups, a single PCM can control both the engine and transmission. On 58x setups, you typically need a separate ECM and TCM. The exception is if you're running a 6L80 or 6L90 transmission, which pairs with 58x controllers.

Does One Make More Power?

No. There's no horsepower difference between 24x and 58x. Some folks say the 58x signal is cleaner at high RPM, but for most street and performance builds, either one works fine. The power comes from the engine, not the reluctor wheel.

Why This Matters for Your Swap

The harness has to match the engine. A 24x harness won't work on a 58x engine because the PCM can't read the crank signal correctly. It'll crank and never fire.

When you order a harness from us, we ask which engine you're running for exactly this reason. Tell us the engine code or year and application and we'll make sure you get the right setup.

If you're not sure which reluctor your engine has, check the crank sensor, its right above the starter. Black connector is 24x. Gray connector is 58x. Or just give us a call and we can help figure it out.

Mixing and Matching

Some builders end up with a 58x engine but want to run 24x electronics, or the other way around. Conversion is possible but adds complexity.

Lingenfelter makes a conversion box that lets a 24x PCM read a 58x signal. Going the other direction usually means swapping the reluctor wheel and timing components, which is more involved.

For most swaps, the easier path is matching everything from the start. Same generation engine, harness, and PCM. Less to troubleshoot, faster to get running.

Bottom Line

24x is Gen III. 58x is Gen IV. They use different harnesses, different PCMs, and different cam sensor locations. Neither one makes more power than the other. What matters is that everything matches.

If you're not sure what you have or what you need, call us. We'll get you the right harness for your engine and make sure it's set up to work the first time.