factory aluminum trunk lid... check this out
I've never seen a mention of an aluminum trans crossmember, just the transmission
case. Some people have also commented on lighter fenders and other parts, but that wasn't the case.
http://www.valiant.org/duster.html
http://en.wikipedia.org/wiki/Plymouth_Duster
Parts are hard to find considering the 1-year only production. Just remember to bring a magnet when looking for the cars or parts!