The Generation III V-8 engines replaced the Gen II-LT family in 1997 and Gen I completely by 2002. Like the previous two generations, the gen III/IV can be found in many different brands. The engine blocks were cast in aluminium for car applications, and iron for most truck applications (notable exceptions include the Chevrolet TrailBlazer SS, Chevrolet SSR and a limited run of Chevrolet/GMC Extended Cab Standard Box Z71 Trucks). The architecture of the LS series makes for an extremely strong engine block with the aluminium engines being nearly as strong as the iron generation I and II engines and with the iron LS engines far exceeding the capabilities of the previous two generations. The engine also introduced coil-near-plug ignition. The traditional five-bolt pentagonal cylinder head pattern was replaced with a square four-bolt design, and the pistons are of the flat-topped variety (in the LS1, LS2, LS3, LS6, LS7, LQ9 and L33), while all other variants, including the new LS9 received a dished version of the GM hypereutectic piston. The cylinder firing order was changed to 1-8-7-2-6-5-4-3, so that the LS series now corresponds to the firing pattern of other modern V8 engines (for example the Ford Modular V8).
Info taken from Wikipedia
The LS series engine is now the most desired motor for engine swaps for almost any make or car. I will be posting pics of different cars with LS transplants in the near future.
Here's a few pictures and solid model of the greatest motor GM has ever built.