Early 70s vintage original SB Mopar/Chrysler/Dodge/Plymouth 4V intake manifold. This is what MoparChat says about it:
"if you're looking for the best cast intakes........these are it, good luck finding them.......
3512100
3614825
3671918
3698434 this is the best one"
Carter carb (spread bore) bolt pattern. Markings read: 8ZC 3698434 AL FIRING ORDER 18436572. I'm told originally fr 340; also fits 318 & 360 (possibly 273?) as well. $125 20 min N of S'toon.
UPDATE: SOLD!!! Thanks Terry!