The previous generation '96-'99 GM fullsize trucks and SUVs are excellent workhorses that put tons of miles under their bumpers without a whimper. However, the 305ci and 350ci small-block V-8 powerplants can definitely use a little help in the power department. For that reason, we're showing you how to swap an emissions-legal 383ci GM Performance Parts V-8 crate engine into your '96-'99 GM truck or SUV for a healthy increase in torque and horsepower.
The best place for us to start the engine swap was to order a GM Performance Parts HT383E replacement engine. The engine showed up in a crate, like this one, and was removed upon delivery by cutting the banding wires to make sure all the parts are in the crate.
383 PowerTo get started, a GM Performance Parts HT383E V-8 engine, part number 1249910, was ordered from Scoggin-Dickey Parts Center, an Authorized GM Performance Parts dealer in Lubbock, Texas. The pros at Scoggin-Dickey recommended this engine because it was designed to provide 'truck-usable' power-low rpm grunt with excellent efficiency-and will bolt into the truck just as a 350ci replacement engine.
The HT383E engine uses a cast-iron engine block and heads and a forged-steel 3.800-inch-stroke crankshaft, in place of the 3.480-inch crankshaft usually found in 350ci engines. The longer stroke crank combines with aluminum pistons in the traditional 4.000-inch small-block V-8 cylinder bores, to attain the 33-ci increase to 383 ci.
The dyno results make it clear this is a truck engine-with ratings of 435 lb-ft of torque at 4,000 rpm and 340 hp at 4,500 rpm. That kind of down-low power makes this engine ready for stump-pulling or hill-flattening, when needed. In fact, this grunt-daddy makes more than 400 lb-ft of torque from 2,500 to 4,000 rpm.
The air-cleaner system needed to be removed. This was started by removing these two electrical connectors (arrow A points to the mass air-pressure sensor, arrow B to the inlet air-temperature sensor), after disconnecting the battery negative cable. To remove the connectors, we lifted the lock tang approximately 4 mm (see inset photo). We removed the fan shroud next. After taking out the 10mm bolts holding it in place, we lifted the shroud out of the vehicle. We then removed the small wiring conduit from its clip and moved it out of the way to remove the shroud. | 
Next up was the removal of the components connected to the engine, starting with the throttle and cruise-control cables. We did this by opening the throttle about 75-percent with our hand, then we pulled the cruise-control cable end outward, slid the mounting tang back off, and then unthread the throttle cable from the cam. |
We then removed the two bolts (see arrows) holding the alternator on its mount, then removed the electrical connector and 10mm nuts holding the power wire on the back of it. We lightly pried the alternator out of its mount and set it aside until the reinstall process. | |