1nastyss

iTrader: (12)

I am looking at a set of heads that a guy said are the Stage 2.5 ported Ls6 heads from TSP, they came off his 06 GTO, i just want to know what to look for to make sure they are not just his stock heads....Let me know fellas

RRhodes1

mine have the area where the cast numbers are cast milled off and a "PRC" logo milled into them. verify that they are LS6 heads by looking for a casting number in the lifter/pushrod valley area on the head.

1nastyss

iTrader: (12)

Now im not sure if they are the 6.0 ported 2.5 or the LS6 ported 2.5 heads....Either way, either head will work, right?

danbo313

iTrader: (8)

Look in the intake port for the absence of casting lines or seams. Also it should look like the surface has been machined inside the ports and not just cast.

hammertime

iTrader: (1)

LS6 and GTO 6.0L heads should be the same, except for valves. 2.5 heads won't have the stock valves anyway.

If you mean the 6.0L truck heads (317) then they are different castings, larger combustion chambers.

Porting should be easy to see if the heads are off the car.