Factory Aluminium Intake for 258 AMC?

I was looking under the hood of my newly bought '80 Eagle. The engine had been steam cleaned pretty throughly. As I zero'd in on the intake,I thought run my fore finger on the intake,some old Blue paint flaked off reveling what LOOKED Like ALUMINUM. I poked around a little more and and sure enough,more "dull Silvery like finish" appeared on the manifold. Kinda Neat I was wondering if it was a factory piece(well,DUH IT IS A FACTORY Piece) :roll: ........I was just wondering what it's purpose was? A little less weight on the car overall? Emmissions? I already looked at my '78 Concord/DL,and sure enough---factory cast iron. HMMmmm. Makes ya wonder though OO6.

Now you have to polish it.

My AMC Concord DL had an alloy intake for a 2 barrel carb, mopar automatic tranny, carb bores wern't but an inch or so. If only I had be smart enough to install a 350 holley!

I know I'm replying to a kinda old post, but I just found this place!
In 1980 (calendar year, not model year -- the AMC engine plant worked off calendar year for some odd reason), the AMC six had a diet! Beginning sometime in January 1980 the "light weight" version was introduced. It shaved 40 pounds total off the engine weight. Slightly thinner iron castings, aluminum intake, four counterweight crankshaft, and 7/16" head bolts. In 1987 the head bolts went back to 1/2", though no Jeepers have ever reported problems with 7/16" bolts. The old crank was 12 counterweight and a good bit heavier, around 15 lbs heavier, but the newer light one is just as strong for most uses. I've not heard any reports of crank breakage, even from rock crawlers (no more than for the heavy crank anyway). The 4.0L uses the same type crank (four counterweight) and is essentially the same casting, just no provision for a mechanical fuel pump and a larger bore (258 can't be bored to a 4.0L bore). The 4.0L and longer stroke 258 (4.2L) cranks interchange, 258 crank in 4.0L block gives a 0.44 stroke increase, 4.5L.