LQ9 In a 1970 Suburban

[Critter]

Originally Posted by OldCreek

Its a 6.0L GenIII LSx motor. Probably the highest output truck motor of that generation...correct me if i'm wrong. It's just like the LQ4 but with flat top pistons (not dished) so it has a bit higher compression and, therefore, rated for more hp/tq. Iron block, aluminum heads. Was found it the Heavy Duty line of GM trucks and in some Cadillacs.

I think you were spot on until your last sentence. The LQ9 (345 HP) was found in the Escalade, Chevy SS Silverado, and the Chevy/GMC Vortec Max, all which are "light duty" 1/2 ton platforms. The LQ4 (300-325 HP depending on the application) was the engine in the "heavy duty" 2500 and 3500 trucks, along with 3/4 ton Vans, GMC Denalis, 3/4 ton Suburban, 1500 HD, and the Hummer H2. Basically everything I said here is applicable for the older body style vehicles i.e 1999-2006.

By 2007 you start to see the LY6, L76, LFA, L92 which are similar but different.

...somebody correct me if I am wrong.