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  • Standard order lead time for STANDALONE WIRING HARNESSES is estimated to be 9-11 weeks from date of purchase.

    Need is sooner? Give us a call to discuss expediting. Limited slots available.

    All other items typically ship within 3-5 business days unless specified otherwise.

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Home > Gen IV LS / Vortec Harnesses

Gen IV LS / Vortec Harnesses

All pricing shown is for our default harness layout which is a 42" long harness that originates off the passenger side rear head. Custom layouts are available for an additional fee. Call to order a custom layout harness.
We have been building standalone wiring harnesses for the Gen 4 (58x) LS platform of engines since their inception.

We developed the first LS standalone wiring harness around 1996/1997 and have been building them in-house for thousands of automotive enthusiasts and professional companies around the world since then.

We build our LS swap harnesses on one of the many different live engine and transmission setups we have in-house which closely reflects the swap you are performing in your project at home or in the shop!

It is because of this process, our harnesses are the best running, looking, and fitting available.

The other major benefit of having us build your LS swap harness on one of our live engine and transmission setups is that we actually test run each and every harness we build prior to shipping. While your harness is running the engine, we have OEM GM diagnostic hardware and software hooked up to verify our work, and to help ensure trouble free operation once you receive the harness.

Once the LS swap harness has passed all of our diagnostic run tests, we cover it with our exclusive, heat resistant, woven fabric covering. This isn't a cheap see through plastic mesh covering, this is a nice quality covering and offers the correct fitting finish to your new Speartech harness that our customers expect.

The process and practices we choose to use takes a little more time, but we feel are necessary steps in order to ensure the end user has a good experience and gets something that "just works", and with proper installation, we know it will - we have already tested it on a live engine and transmission!

Put 23 years of GM Engineering experience - and now over 20 years spent perfecting the LS swap harness manufacturing process - to work for you!

We support all combinations of Gen 4 LS / Vortec engines with any compatible transmission including LS3, L99, LS7, LSA, LS9 and 5.3 / 6.0 / 6.2 Vortec truck variants, etc.

In addition to being the first to market for Gen 4 LS standalone swap harnesses, we also headed development on being able to use 6L80 and 6L90 transmissions for swap use. Early on, we understood that having a six speed automatic with tap shift capabilities would be a popular option hot rodders and LS swap enthusiasts would want to have in their swapped vehicle. Because of this, we developed products and programming calibrations which enable you to take full control of your 6L80 or 6L90 transmission. We offer a full range of functional tap shift, neutral safety switch, reverse light, and other 6L80 / 6L90 related products.

All harnesses are built to order, and a full range of customization options are available to you. Whether you want your computer in the trunk, are running a supercharger or a "high ram" intake manifold, or any other aftermarket item that may change sensor/connector placements, etc., we can accommodate your customization requests. You don't have to run adapters or extensions, we build it just how you request it. We will create a custom harness layout draft and send it to you for approval before starting on your harness build if your project requires it.

Feel free to give us a call at (765) 378-4908 or email info@speartech.com to discuss options, pricing, more info, or to get your Speartech harness build in the works!

All harnesses include instructions, every wire labeled, and an OBD2 port with integrated check engine light for easy diagnostic checks down the road.

We can also handle your computer programming needs. Whether we are providing a programmed computer, or we are reprogramming one you supply, it will be tested together with your harness while running the engine!

If your LS swap harness doesn't require much customization, feel free to browse our harnesses below. You can fill out some quick information and place your Speartech harness order online. As always, feel free to give us a call prior to purchase with any questions you may have about our products. We are here to help!

We offer our Gen IV 58x LS swap harnesses in 2 ways. The standalone swap harness itself, or a complete harness package which includes our standalone swap harness, programmed ECM, programmed TCM (if applicable), and an easy to mount electronic throttle pedal.

Speartech - The Original and Still The Best!