What are the internal differences between these 2 years. I have an 04 LQ4 6.0l right now but 3 pistons have skirt damage but the bore is fine.. Can I use pistons/rods out of a 99 LQ4 6.0l??

Thanks...

 

bottom end is the same. 01 up got aluminum heads.

 

Rotating assemblies are the same (other than the crank end-pad thickness on the '99-'00)......but there is at least one block difference, the '01-up 6.0 blocks have a better main oil gallery design that was inherited from the 5.7

 

i wouldnt put a 99 engine in my truck, or even buy a 99.

 

Somewhere around '03 they got coated skirts on the pistons. My '01 did not have this but the crate motor I purchased in '04 did. I don't see any reason why you couldn't use the non coated pistons in the newer motor.

 

The block would probably just need to be honed for the coated pistons.

 

Should be no problem to use the pistons/rods for LQ4 to LQ4.
Make sure NOT to use the crank, the flexplate bolt flange is slightly thicker on the 99 model and would cause TC/tranny mounting woes.