The Common Rule
Most Gen III LS-family combinations use a 24x crank trigger and 1x cam signal, while later Gen IV combinations commonly use 58x crank and 4x cam signals. Chevrolet Performance's LS controller documentation describes its 58x/4x standalone systems as typical of 2006-and-newer engines.
Sensor Clues
Holley's LS overview notes that common 24x crank sensors use a black body while 58x sensors use a gray body. PSI likewise recommends identifying the reluctor/controller system before choosing the harness.
| Common Gen III pattern | Common Gen IV pattern |
|---|---|
| 24x crank signal | 58x crank signal |
| 1x cam signal | 4x cam signal |
| Rear cam sensor common on early engines | Front cam sensor common on later engines |
| Drive-by-cable common in trucks, DBW also exists | Drive-by-wire common |
Exceptions Are Why You Identify The Actual Parts
Do not use model year alone. Early LS2/LS4 applications and mixed-part engines can blur the simple Gen III/Gen IV rule. Verify the reluctor/sensors, controller family, harness connectors and cam timing hardware on the actual engine.
Sources & Further Reading
These links are here so you can verify the numbers and go deeper into the original technical material.