The LS family is the parts-yard’s best answer for an affordable car swap — cheap iron-block V8s that drop into a Miata, a 240SX, an S10, or a square-body pickup where a modular Ford small-block never quite fits. Two cast-iron variants sit on every shortlist: the 5.3 LM7 / LR4 and the quieter 4.8 LR4. This comparison runs the five numbers every car-swap build turns on — block and casting, weight, power ceiling, swap cost, and parts availability — so the right engine gets bolted in behind the radiator.
The 4.8 is the 5.3 block bored and stroked shorter. Same family, same deck height, same Gen III architecture.
Both engines are the same Gen III / Gen IV small-block LS architecture, but the 4.8 is the short-stroke variant of the same block. The 4.8 LR4 carries a 3.78 in bore and a 3.27 in stroke; the 5.3 LM7 / LR4 carries the same bore and a longer 3.62 in stroke. Shared deck height, shared 5.7 L bore-spacing, the same head-bolt pattern. The 1998–2003 4.8 LR4 ran in the Escalade, Tahoe, Yukon, Silverado, and Sierra; the 1999–2007 5.3 LM7 / LR4 ran across the same platforms plus the Express / Savana vans. A 4.8 short-block and a 5.3 short-block are the same part with a different stroke bolted into it.
The 5.3 is about ten pounds heavier dressed. The 4.8 carries less reciprocating mass on the nose.
Dressed weight is the headline. The iron-block 4.8 LR4lands at roughly 165–175 lb with intake, accessories, and stock pan. The iron-block 5.3 LM7 / LR4runs 175–185 lb dressed — about ten pounds over the 4.8 because of the longer crank stroke and longer rods. The 5.3 isn’t dramatically heavier, but the 4.8’s shorter stroke carries less reciprocating mass at the snout of the crankshaft, which matters in tight engine bays. The Miata, the 240SX, the small F-body chassis all treat front-rear weight bias like a religion, and a 4.8 pays off there. The S10 swap, the square-body pickup, the 4×4 truck build — none of those notice the ten-pound difference, and the 5.3 still drops in with stock swap mounts.
Stock for stock, the 5.3 wins on torque. Built for built, the 4.8 closes most of the gap with the same parts.
Stock, the comparison is straightforward. The 1999–2003 4.8 LR4 shipped at 270–295 hp and 280–305 lb-ft. The same-year 5.3 LM7 / LR4 shipped at 270–310 hp and 320–335 lb-ft — same horsepower, more torque, because the longer stroke gives the engine more breathing room across the rpm band. Built, the two converge — a 4.8 with a healthy cam, a ported LS6 intake, LS3 heads, and a small shot of nitrous runs with a stock 5.3. For forced induction the 5.3 is the proven platform because LM7 / LR4 has the broader aftermarket and deeper donor pool. The 5.3 wins on stock torque; the gap closes the moment parts go on the bench.
Both engines keep the swap under $4k. The 4.8 runs cheaper on the donor side.
Donor pricing is the cleanest number on the bill. A 4.8 LR4 out of a 1999–2003 Escalade, Tahoe, Yukon, or Sierra runs $300–$700 — the swap market treats it as the “short-stroke 5.3” and prices it just under the LM7. A 5.3 LM7 out of a 2002–2005 SUV runs $400–$900 on the same yard. The supporting parts are identical on both: harness with ECU $400–$900, swap mounts and headers $250–$600, fuel upgrades $150–$400, radiator $250–$500. A 4.8 car swap runs $2k–$3k; a 5.3 swap lands in the $2.5k–$3.5k band. The 5.3 runs about $300–$500 more all-in on a typical build.
Both share the LS parts rack. The 5.3 has the broader donor pool; the 4.8 is a parts-yard “find.”
Both engines are LS engines, so the supporting parts — heads, intake, cam, lifters, oil pan, valley cover, timing set — overlap almost completely. Both fit the same swap mounts (the LS swap kit doesn’t care about displacement), the same harness, the same fuel and cooling upgrades. Where they diverge is the used market. The 5.3 has the wider pool because the LM7 / LR4 shipped across millions of 1999–2007 trucks, SUVs, and vans. The 4.8 LR4 only shipped in the 1998–2003 run, so the donor market is narrower and the salvage pickings drop off a year earlier. The 4.8 is a parts-yard “find” — the 5.3 is a parts-yard “standstill.”
Pick the 4.8 for light, cheap builds. Pick the 5.3 for torque and power.
For a light, cheap swap — a Miata, a 240SX, an F-body, an S10 with a weight target, a C10 build — the 4.8 LR4 is the right pick: cheap donor, lighter nose, the same TTY head-bolt pattern, the same swap mounts. For a torque ask on the sheet — an S10 5.3 swap, a full-size F-body, a square-body build, a 4×4 truck — the 5.3 LM7 is the right pick: broader donor pool, higher stock torque, an aftermarket standing on the LM7 / LR4 for twenty years. Both swaps land in the LS family, and that’s the punchline — the torque list, the fastener sequence, the callouts, and the build worksheet in the LS 5.3 Builder’s Guide carry straight over to a 4.8 swap because the LS family shares the fastener list; 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. For the quick-scan version before you choose the exact fastener, keep the LS swap torque specs reference open beside the build sheet.