GMEFI Magazine

This summer, I got roped into a “honey-do” project with my friend and coworker Jesse Smith. His wife still owns the same Chevy pickup her dad got for her in 1998 while she was a senior in high school; a one-owner, short-bed OBS 1500. It is by far one of the cleanest 25-year-old trucks I’ve ever laid hands on. At first, I figured this would just be a slight refresh, boy was I wrong. For Jesse, this wasn’t just another project, this truck had to be perfect.

Originally, the truck rolled off the lot with a 4.3L V6. But Jesse’s wife always wished it had a V8. In 2007, her soon to be husband yanked an LM7 5.3L and 4L60E out of a wrecked 2001 Silverado to start the process. Back then, LS swaps were still uncharted territory for the most part. Off-the-shelf kits simply didn’t exist yet. Jesse spent nights dissecting wiring diagrams, splicing harnesses, and fabricating parts in order to get it to work “Just like it was originally equipped” as per his wife’s request. The ABS, cruise control, and all ran flawlessly for almost two decades and well over 100,000 miles.

When the original GM “pancake” A/C compressor finally gave up, Jesse saw it as the perfect excuse to tear it all apart and rebuild the truck for his wife with modern hardware. The new plan called for ditching the old-style A/C for a more compact Sanden SD7 unit, mounted low for a cleaner look. That seemingly insignificant change quickly snowballed. Moving the compressor to the bottom meant moving the engine forward with new Dirty Dingo sliding mounts, notching the frame out, new headers and exhaust system. It was at this point that we decided that nothing was off the table for updating.

Though everything else was being updated, the heart of this OBS Chevy stayed true to the original recipe: a 5.3L backed by a 4L60E. The only change was this time he decided to forgo the LM7 iron block for an aluminum block LM4, dropping 100lbs off the nose. Before dropping it in, we couldn’t resist adding one of Scoggin Dickey Parts Center’s 214/218 cam kits paired with a Trailblazer SS intake manifold. Ground on a 111 LSA, the cam gives the truck a subtle but satisfying lope through a new set of Schoenfeld 1 ¾ Inch headers, while waking the little 5.3 up to around 430 horsepower! A Circle D 1,800-2,000 RPM stall converter helps the reman GM 4L60E handle the added grunt.

For engine management we wanted something clean, modern, and easy to use, so we went with Holley’s Terminator X Max. That choice simplified a lot of the installation with the standard 4,000 PPM speed signal for the speedometer. Fan and A/C control was handled with an MSD smart relay, capable of high and low triggers and four separate outputs. The cruise control on the OBS trucks is independent of the ECM and all it requires is to split the speed signal that is going to the instrument cluster.

The stock ’98 gauges were surprisingly easy to integrate as well. Coolant temp, oil pressure and volts are all mechanical, leaving only tachometer and fuel level to sort out. A simple tach signal converter turned Holley’s V8 output into a V6 output that the cluster was looking for since this was originally a V6 truck. As for the fuel gauge, this was handled by Holley’s Classic Instruments Fuel Link module. This stand-alone module solved that problem with ease!

We even tackled the garage-filling fuel smell that plagues many swaps. By wiring the Holley to trigger the EVAP solenoid based on tank sensor input, the truck retains a working vapor recovery system just like the factory did. It’s this kind of detail to things that most people skip, but it is also the difference between calling something “done” or calling something “finished.”

This little RCSB OBS Chevy came out better than new, packing the kind of power we all wish GM had built them with from the factory. With modern A/C, a 430-horsepower aluminum 5.3, factory gauges, and OEM-level drivability, it is ready to power through another 100,000 miles. From the cam’s choppy idle to the low-mounted compressor that cleans up the engine bay, every detail was executed with purpose.

Those details under the hood back up the truck’s stunning looks, with American Racing Torque Thrust IIs, a paint-matched Snug Top bed cover, and the absolute perfect stance. It is more than just a clean OBS; it is now a showpiece that runs as good as it looks. Jesse’s wife finally got the V8 she always wanted, and this Chevy is built to last a lifetime of car shows, cruises, and good memories.