Just to let you know, the factory GM unit (no longer available) that cracked is stainless. I was told by a hedder manufacturer that GM used such a cheap grade of stainless steel to produce the turbo regal hedder and the heat created by the heat shields was the cause of the cracks on the factory hedder. The Poston unit is not stainless, but is coated (inside and out). This also does not guarantee it will not crack, as I heard some board member claim their Poston units cracked. But mine seem to be just fine. The coating on the hedders allow the exclusion of the heat sheilds, hence they are not sold with heat sheilds. I wouldn't go though the trouble to remove the factory heat sheilds to install them on my new hedders anyhow.
