the difference between lq9 and lq4 just bought a 6.0 and want to know. I know on the heads it has 317 stamped on it, but I dont know if that helps.

 

get the serial number and take it to a gm dealership. Besides that You would have to look at the pistons.

 

pull the spark plug and look in there to see whether it has dish top or flat top pistons.

dish top = LQ4
flat top = LQ9

the dish top will have a little raised ridge around the outer edge of the piston. The flat top will be, well, flat, lol.

 

If the engine is out of the truck then pull a plug and with a flashlight look and see if it is a flat top or dish piston. LQ9's have flat-tops.
Here is a pic and info in this thread.
here

 

great find MJ

Here's a direct link of the pic

 

sniff em you can normally tell an lq4 by the smell

 

I did the flash light in the spark plug hole trick on mine yesterday. It's a little hard to see, but I saw the dish tops on it.

 

What year engine is it? I know the 99's have a wider flange at the back of the crank for use the the 4l80 transmission.

 

or look at the flexplate, LQ9 has a smaller bolt pattern and a LQ4 has a larger onesince one uses a 60/65 and other uses 80

 

will this affect the way the transmission bolts up?

I've got an LQ4 and will be bolting up a 4L60E to it(I know, I know, it will fail)...but is there anything I need to change up for that? Everything should bolt up, right?