The LS family is the swiss-army knife of the truck-swap world — affordable, plentiful, and forgiving enough that a weekend wrencher can finish a build without trashing the engine. Two cast-iron variants sit at the top of every parts-yard shortlist: the 5.3 LM7 / LR4 and the 6.0 LQ4 (with the rarer aluminum LQ9 as a third option). This comparison runs the four numbers every truck-swap build actually turns on — weight, power ceiling, swap cost, and parts availability — so the right engine gets bolted behind the bumper.
The 6.0 weighs more than the 5.3 — but the gap is narrower than most build threads claim.
Dressed weight is the headline number. The iron-block 5.3 LM7 / LR4 lands at 175–185 lb with intake, accessories, and a stock truck pan. The iron-block 6.0 LQ4adds bore for around 200–215 lb dressed — call it 25–30 lb over the 5.3. The aluminum LQ9 trims back to roughly 195–205 lb dressed, sitting between the iron 5.3 and the iron 6.0. Twenty pounds either way isn’t a dealbreaker, but the 6.0’s taller deck asks for more hood clearance, the wider bore needs frame-rail clearance on a few chassis, and the long‑block is just long enough that some transmission-tunnel templates stop lining up. The 5.3 drops into spaces the 6.0 won’t; the 6.0 still drops into every swap kit a shop sells as standard.
Stock for stock the 6.0 wins. Built for built, the 5.3 closes most of the gap.
Stock, the math is straightforward. The 2003–2007 5.3 LM7 / LR4 shipped at 270–310 hp and 320–335 lb-ft. The same-year LQ4 6.0 truck engine ran 300 hp and 360 lb-ft from the factory. The aluminum LQ9 (Escalade EXT, Sierra Denali) came in hotter at 345–385 hp / 380–415 lb-ft, mostly because the intake plenum and cam were spec’d for the luxury half-tons. Built, the two engines converge — a 5.3 with a healthy cam, a ported LS6 intake, LS3 heads, and a small shot of nitrous will run with a stock 6.0 for a few hundred dollars in parts; a 6.0 with the same upgrades still wins on torque everywhere on the dyno sheet and pulls boost harder because the block is stronger from the casting floor up. For a daily-driven truck swap, the power ceiling gap is smaller than the parts list suggests.
Both engines keep the swap under $4k when you shop the right donors.
Donor pricing is consistent. A 5.3 LM7 out of a 1999–2007 Escalade, Silverado, Tahoe, or Sierra runs $400–$900 — the sweet spot is the 2002–2005 SUVs with the higher-nickel block. A 6.0 LQ4 from a 2002–2007 SUV or 2500 truck runs $600–$1,200 on the same yard. The aluminum LQ9 is the rarest donor of the bunch and runs $900–$1,800 — it only shipped in the Escalade EXT and the Sierra Denali from 2002–2007. The supporting parts are the same on both engines: harness with ECU $400–$900, mounts and headers $250–$600, fuel upgrades $150–$400, radiator $250–$500. End-to-end a 5.3 swap in a clean donor chassis runs $2.5k–$3.5k; a 6.0 swap lands in the $3k–$4k band. Well under $4k is realistic for both.
Both engines share the LS parts rack. The 5.3 is denser on the used market; the LQ9 is the rarest of the three.
Both engines are LS engines, so the supporting parts — heads, intake, cam, lifters, oil pan, valley cover, timing set — overlap almost completely. The differences show up in the rotating assembly: the 6.0 has a longer stroke and a stronger rod, the 5.3 has a lighter piston and a shorter crank. On the used market the 5.3 has the edge — the LM7 and LR4 shipped in millions of 1999–2007 trucks, SUVs, and vans, so parts-yard inventory will stay deep for another generation. The 6.0 LQ4 is nearly as plentiful in the same year range. The aluminum LQ9 only shipped in the Escalade EXT and the Sierra Denali, so the donor pool — and the salvage castings — are narrower. When availability is the deciding factor, the 5.3 wins; when a dent-aluminum block matters more than donor count, the LQ9 is the right find even if the parts rack has to work harder for you.
Pick the engine that fits the build sheet, not the build thread.
For a daily-driven truck swap the 5.3 is the cheapest, lightest, and most-supported path. The 6.0 LQ4 is the higher-torque, stronger-blocking choice when the build budget can stretch a thousand dollars and the chassis can swallow a slightly taller deck. The aluminum LQ9 is the rare third option — the one to chase when a dent-aluminum block, lower weight, and 380+ lb-ft of stock torque all matter. In every case the bench work is the same: the same torque list, sequence, and callouts. The torque values, the fastener sequences, the callouts, and the build worksheet in the LS 5.3 Builder’s Guide carry straight over to a 6.0 swap because the LS family shares the fastener list; and for the actual torque spec to set the wrench to, the companion Torque Specs & Sequences manual drops the pull-list to a single printable page. Pick the engine the build budget and the chassis can carry, then bolt the same book onto the bench either way.