Stock PCM vs Holley Terminator X for an LS swap
Stock GM PCM: cheapest (it often comes with the junkyard engine), proven, and it runs the transmission it was paired with. It needs a standalone harness and a tune (VATS delete, injector/MAF data). Speedway recommends it for most swaps unless you're building a lot of power. DIY cost can be about $400 if you already own the PCM and tuning software.
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Holley Terminator X: engine-only, self-learning EFI. Terminator X Max adds drive-by-wire throttle and 4L60E/4L80E control built in, plus 6L80/6L90 with Holley's 558-499 kit. It's better suited to heavily modified or boosted engines and frequent changes, and it includes the harnesses. It costs more, and GM PCMs handle factory-specific items (gauges, some emissions) that aftermarket units don't.
Rule of thumb: mild cam-and-headers swap with a donor PCM, use the stock PCM. Power adder, lots of changes, or no donor PCM, use a Terminator X or X Max.
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- Holley's Terminator X Vs. GM Standalone ECU For LS Swaps — LSX Magazine
- Squarebody LS Swap Guide | 73-87 C10 Parts List — Speedway Motors
- Squarebody LS Swap Guide | 73-87 K10 Parts List — Speedway Motors