What is is, and how much is it worth?

I was told these are rare. Cast steel. Numbers are

Firing Order :18436572

D<>N

16

14096242

3 12 92

GM
Chevy Logo

Here are pics

Thanks alot for any help


http://img.photobucket.com/albums/v2...f/IMG_7326.jpg

http://img.photobucket.com/albums/v2...f/IMG_7325.jpg

http://img.photobucket.com/albums/v2...f/IMG_7324.jpg

http://img.photobucket.com/albums/v2...f/IMG_7323.jpg

http://img.photobucket.com/albums/v2...f/IMG_7321.jpg

It looks like the spreadbore marine intake..... 1.25 inches
taller than a typical stocker. Boat guys use them, most
dirt tracks wont allow them.

You see them in really nice shape selling for $100-125. Other than marine use, the only attraction is if someone is trying to make a motor that looks original but has a little more.
Never saw this part number claimed to be as good as an aluminum manifold.