1971 duster 318 head pipes/drop downs

here's a few resources:

https://www.ttiexhaust.com/Classics_ExhaustComponents.htm#Exhaust-pipes

https://www.accurateltd.com/A-Body-318-340-and-360-Head-pipes-Pair_p_194.html

https://www.manciniracing.com/expimpi2.html