Quote Originally Posted by Gradient View Post
The 5.3L is not a factory muscle car engine, it's the half ton PU and Tahoe platform engine. However, it is swapped into muscle cars because it can handle a lot of boost on the stock bottom end (iron block version). Same goes for LQ9 6.0L engine.
Not all 5.3L GM gassers are equal. The LS4 was never a light truck engine, and shouldn't be confused with other historical "LS" series engines. They were OEM in late model "muscle cars" brands, such as Monte Carlo and Grand Prix (in transverse configuration), among others. The LM4 is the aluminum block light truck engine, the LM7 is cast iron. There are numerous "5.3L" engine option configurations from 1999 to present model years. There is no correlation between any of them, and late model 6.0/6.2L gasser engines. Different animals, with very different applications and control systems. The 6.0L LQ4/9 light truck engines are unique unto themselves, not to be confused with the "LS" (and other) series 6.0L's.