I've also read that they used an aluminum trans mount/cross member, the aluminum intake (as mentioned), and the case of the A-833 OD was aluminum as well.
The reports I read said that with the 4spd OD and 2.90 rear gears, the cars were good for 36mpg highway.
I'd love to find a hood and decklid for my '73... If I was anywhere near St. Louis, I'd have that one.
-Brad