GM first released the Gen-III 5.3L truck V-8 in 1999 in the Silverado and Sierra truck platforms. GM Performance Parts (GMPP) has taken notice of the millions of these and the 4.8L V-8s that have been placed into '99-'05 trucks and SUVs, and released a bolt-in performance replacement—the LS327. Producing 327 hp and 347 lb-ft of torque, the new LS327 can wake up your tired, high-mileage 4.8 or 5.3L and add a whole new level of performance to your daily driver. Not just a relabeled LS-engine, GMPP did some upgrades to the engine by inserting eight Grafal coated hypereutectic pistons and a snappier camshaft with 0.467/0.479 lift and 196/201 duration. The LS327/5.3L HO, comes as a long-block, complete with valve covers, and is compatible with truck and SUV engine accessories. Each GMPP crate engine undergoes 50 hours of high-load durability testing, comes with a 24 month warranty, and with a price tag of only $3,150, you can’t go wrong.

Taking a look at our truck fleet, the '02 Chevy Avalanche stuck out like a sore thumb because of its high-mileage, seemingly worn-out 5.3L under the hood. Calling up GMPP, we placed an order for the new LS327 and lined up a shop to help us with the engine swap. Before we took delivery of the crate engine, we performed a chassis dyno test at the Source Interlink Tech Center. Jason Scudellari, the Mustang chassis dyno technician, made three strong pulls on the dyno to give us an original engine performance baseline. Surprising to all of us, the Avalanche, equipped with 22-inch wheels/tires, a K&N intake, and Magnaflow exhaust, only made 202 hp and 272 lb-ft of torque. Rated at 285 hp (at the flywheel) in '02, that's a loss of 83 ponies over the last 120,736 miles. Scratching our heads, we couldn't wait for the new GMPP LS327 to be dropped off.

The new GMPP crate engine LS327 was loaded into the bed of the '02 Avalanche and delivered to Trader's Sport Truck in Santa Fe Springs, California, for the engine swap.

We photographed the engine swap procedure starting with the removal of the factory 5.3L Vortec that survived 120,736 miles. Some of the original engine external components and accessories were reused on the new LS327 crate engine.