thechef

iTrader: (13)

ok my 2009 G8 GT has the L76 motor and the head casting number is #5362 is that a ls2 head or the ls3 head?? I have never seen that casting number before

HSV-GTS-300

Have another look.
Casting #5364 is the same style of large rectangular intake port heads as LS3.
Yours will have the heavy intake valves and not hollow stem intake valves, otherwise it's the same as LS3. Also yours has less capable valve springs than LS3 heads are fitted with.

Deezl SS

iTrader: (13)

What he said....ls3 head with l92 valves. Is that you CP?

thechef

iTrader: (13)

my understanding is that they are L92 heads with the heavy valves and catherderal ports

Deezl SS

iTrader: (13)

No sir, no catherderal ports.

HSV-GTS-300

Yup.

SLOW SEDAN

iTrader: (13)

If they are L92 heads then they aren't cathedral port. The heads that come with the L76 are like LS3 except for the intake valve and springs as stated. Normally we just swap springs unless you really want lighter valves but its not normally needed or noticed in a street car.