Exhaust manifold question

Part # 2863553
Side: Drivers
Usage:1968-70 Baracuda, Dart with 340-ci
1970-71 Duster with 340-ci and 1970 Challenger.

Part # 3418623
Side: Passenger
Usage:1971-73 Barracuda,Challenger,Dart,Duster,Charger,and Road Runner with 340-ci 1971-73 Fury,Polara, and Monaco with 360-ci without California emmisions.

The 2863553 is the better performer of the two.