LS Swap Parts You Need to Complete the Conversion
An LS swap isn't one purchase, it's eight decisions made in the right order. Skip one and you've bought yourself a second trip to the parts counter at 11 PM on a Saturday. This is the checklist from engine selection through first start, organized the way builders actually hit the decisions — not alphabetized like a catalog.
1. Engine — Pick the Donor, and Understand What You Bought
Four common donor paths, each with its own tradeoff:
- LS1 (1997-2004 F-body / C5 Corvette) — 5.7L aluminum Gen III, 24x reluctor, cam sensor at the rear of the block, cathedral port. Cheaper than it used to be but not the bargain it once was. ~305-350 factory hp. Good swap engine; composite intake is tall so hood clearance needs checking.
- LS3 (2008+ C6 / Camaro SS) — 6.2L aluminum Gen IV, 58x reluctor, cam sensor at the front cover, rectangle-port heads flowing 260+ cfm out of the box. 430 factory hp, easy 500+ with a cam. The modern default for a performance swap when budget allows.
- 5.3L Truck (LM7 / LH6 / LMG / LC9 / LY5 / LH9) — iron or aluminum block depending on variant, cathedral port, huge production numbers make this the budget-swap engine. LM7 (Gen III) is the purist's pick — no AFM, 24x reluctor. Gen IV variants need an AFM delete done before you swap them in, not after.
- 6.0L Iron Block (LQ4 / LQ9 / L96 / LY6) — the boost/stroker foundation. Iron block swallows 1,000+ hp with studs and a Cometic MLS gasket. Heavy — about 80 lb over an aluminum LS. LQ9 has flat-tops for higher compression; L96 and LY6 have L92-style rec-port heads and VVT that usually gets deleted.
Know the generation (24x vs 58x) before you buy anything else — it determines your harness, your crank sensor, your balancer, and your transmission flexplate.
2. Transmission — The 3-Way Choice
- T56 / T56 Magnum — 6-speed manual. The enthusiast default for a swap car. LS1/LS6 came behind the T56; T56 Magnum is the modern strength-upgraded version. Needs an LS flywheel on the correct crank-flange pattern (6-bolt or 8-bolt — 8-bolt on LS7, LSA, LS9, some late LS3). Factory bellhousing integrated; usually used with a hydraulic throwout bearing in a swap chassis.
- 4L60E / 4L65E / 4L70E — 4-speed electronic auto. Behind stock 5.3 and 6.0 trucks. Up to ~450 lb-ft safely; beyond that, builders and upgraded cases. Cheapest auto path; fits tight tunnels.
- 4L80E — heavy-duty 4-speed electronic auto from 2500HD trucks. Handles 700+ lb-ft stock. Larger case, longer, heavier — not every chassis tolerates the tunnel modification. The right call behind a turbo or a stroker.
Flexplate crank-flange pattern is the single most common wrong-part return on the LS platform. Count bolts on the crank before ordering.
3. Harness — Three Paths
- Standalone aftermarket harness — PSI Conversion, Speartech, Current Performance, Howell. You ship them a list of your engine's RPO, transmission, accessories, and what you do or don't want (cruise, traction control, etc.) and they ship back a harness that plugs in and runs. Premium path, zero DIY risk.
- DIY harness modification — you pull the factory harness from the donor and pin out what you need, deleting emissions, evap, cruise, and all the body-integration circuits. Cheapest but time-consuming and unforgiving.
- Factory harness + ECM with tune flash — works on early-generation swaps (LS1 F-body, LS3 GTO/G8) where the original harness can be adapted. Ubiquitous with Holley Terminator X / Haltech / BigComm PRO replacements on advanced builds.
A tune is not optional on any of these paths. If you skip the tune you'll throw codes for the deleted emissions hardware and possibly the wrong VATS/theft module state.
4. Engine Mounts — Chassis-Specific
Every common swap chassis has a purpose-built mount set; don't weld brackets to an engine unless you have to:
- S-10 / Sonoma / Blazer — bolt-in mount kits; tight on the driver-side header because of the steering box
- 240SX (S13/S14) — Sikky, Chase Bays, PRP mount kits
- Miata (NA/NB) — Wilwood/V8Roadsters and similar purpose kits
- Fox Body Mustang — Hinson Motorsports, TrickFlow adapters; headers are the tight spot
- G-body (Monte Carlo / Cutlass / Regal / Grand Prix) — bolt-in factory-style swap kits are widely available
- Classic C10 truck, 73-87 — straightforward
- Trailblazer / Envoy (LL8 to LS2 swap) — factory LS2 Trailblazer SS hardware crosses over
Chassis-specific mount kits also dictate your oil pan and accessory drive — they are not independent decisions.
5. Oil Pan — Driven by Chassis Clearance
Four GM LS pan designs cover most swap scenarios:
- F-body LS1 pan — shallow front sump, clears most steering boxes, common swap choice for 240SX, Miata, Fox Body, and classic muscle
- C5/C6 Corvette pan — center sump, batwing windage tray, wide; great for clearance in some Nissan and Mazda chassis but conflicts with many front crossmembers
- Truck pan — deep rear sump; fits truck and SUV applications natively, clears many classic-truck frames, but hangs too low in most cars
- GTO / Holden pan — rear sump, narrower than truck, the swap-world favorite for G-body and classic muscle where F-body pan sits too far forward
Every aftermarket mount kit vendor specifies the oil pan it was designed around — start with the mount kit, not the pan.
6. Accessory Drive — Truck vs. Corvette vs. F-body
The three factory layouts position the alternator, power steering pump, and AC compressor differently:
- Truck accessory drive — wider, compressor down low, alternator up top passenger side. Sticks out past most stock car fender lines. Cheap from salvage.
- F-body accessory drive — narrower, compressor on driver side. Fits more swap chassis but AC bracket is specific.
- Corvette accessory drive — narrowest (tight belt path), usually premium because C5/C6 cars are less common in the junkyard. Popular for tight engine bays.
Aftermarket brackets (Holley, Kwik Performance, ICT Billet, Concept One) re-layout everything cleanly for specific chassis. The budget answer is "match the pan and drive to the donor"; the clean answer is an aftermarket billet bracket set designed for your chassis.
7. Fuel System
- Returnless (LS3, LS2, most trucks 03+) — uses rail-integrated fuel pressure regulation; simplest. Pump in the tank at 58 psi is usually enough for N/A swaps up to mild performance.
- Return-style conversion — needed for most LS1/LS6 and any higher-flow build. Adapter rails with a bypass regulator, or aftermarket rails with -AN plumbing.
- Pump sizing — stock in-tank for N/A LS3-level N/A. Walbro 255 for mild boost or 500 hp. Twin 340 LPH or a single high-flow (DeatschWerks, AEM E85) for serious boost / stroker builds.
EV1 vs EV6 injector connectors — EV1 (Multec-2 square) is LS1, LS6, early LS2, early truck; EV6 (USCAR oval) is LS3, LS7, L92+, most Gen IV. Your harness, rails, and any aftermarket injectors all have to match.
8. Cooling
- Electric fans — SPAL dual fans with a low-profile shroud fit most tight swap chassis; temperature switch wired off the ECM fan outputs or a standalone controller.
- Radiator — most swappers go to a crossflow aluminum radiator sized for the chassis; LS thermostat housing locations dictate upper hose routing.
- Upper/lower hose routing — truck and car LS use different thermostat housing angles; the pan of the radiator dictates which one fits clean.
- Heater core circuit — stock LS has two heater lines from the passenger-side head and the water pump. Most swaps loop them together if the chassis doesn't use an LS heater setup; leaving them open-ended causes air pockets.
What to Do Next
- Pick the donor engine and confirm 24x vs 58x, 6-bolt vs 8-bolt crank flange, AFM vs non-AFM
- Pick the transmission to match the chassis tunnel and torque target
- Order the mount kit for your chassis — this locks the pan and accessory drive choice
- Pick the harness path (standalone vs DIY vs factory-reflash)
- Source fuel system and cooling sized to the build
- Shop LS Swap Central and the chassis-specific hub for your car