The reason that LS engines are so good and popular is that the LS engine is made much better and is a more reliable engine than even the original Chevy 350 engine.
The pistons are made stronger, the connecting rods are made stronger as well and the crankshaft is also made stronger.
As long as you maintain the LS engine as in changing the oil often the LS engine could last 500,000 miles or even longer.
LS engines seem to have more power than the regular engines as well.
The LS on Chevy Motors or LS Engines stands for "Luxury Sport".
LS engines are mostly in Chevy Sports cars but some trucks and other vehicles have the LS engine in them as well.
Some people have also swapped out the original Chevy 350 engine for an LS engine because the LS engine is supposed to be a much better engine.
Although if you do swap out an original Chevy 350 engine for an LS engine you need to replace and upgrade the computer so that the Chevy LS engine runs and runs properly.
I replaced a Chevy 350 engine in a 1970's Chevy Truck for an LS engine and it seems to run better and have more power and get better fuel mileage.
Also before the truck had a carburetor and now it has fuel injection which helps with the fuel mileage as well but it took some work and money to switch things over.