5.3 block

[txarkitekt]

...
If this motor has the original heads on it...

yup, the only way its not a L33 is if 1. the person installed the 799 heads on a normal 5.3 block

EXACTLY

if its a early Gen 4 engine because some of them had 799 heads also.

An L33 is a Gen III motor. No Gen IV L33 motors were made. The LH6 is the Gen IV aluminum 5.3L motor...and the LC9 is the FF aluminum 5.3L Gen Iv motor.

But like I said--he needs to go look at the motor and check for casting numbers.