Im about to look at a lq9 for 1000. How can I be sure its an lq9?? It has 317 heads

 

Pull plug

Get long skinny flat head screwdriver.

Stick long skinny flat head screwdriver into plug hole.

If you feel a ridge on the piston it's LQ4 (low compression) if it feels completely flat across top of piston is LQ9 (high compression).

 

It may also have "Vortec Max" engine covers.

 

it would stamped on the block front and rear also.