i bought a set of heads today cast #s are 12578452. i contacted gm today and tried to get an answer they gave me a casting # of 12578450 is there any body out there that can tell me what i might have.

 

All surfaces of intake ports, exhaust ports, and chambers will be machined, not cast. I've got a set at home, I'll look at them later. I believe they also have 7.0L cast in like the block does as well.

 

Those are bare LS7 heads. That is the only casting number for the LS7 heads as far as I can find, for what it's worth

EDIT - And I just looked at a set here to make double sure!

 

i looked at them a little closer and found 7.0 inside the head on the bottom thanks man

 

12578452 = CASTING #
12578450 = PART #

Both #'s correspond to LS7.

Typically GM part #'s = casting # - 2.

 

Eh, I'd say that many times the casting number and part number are similar, but just as often, if you really look into it...they are completely different. For instance, there can be handfuls of different part number, all varying quite a bit, and all of them have the same casting number.

 

Agreed. I think anyone who deals with GM knows there is NOTHING set in stone.

 

Agreed!