1973 360

Rear axle ratios the same?

3.91 was available in 1970 while 3.55 was the highest available ratio in 1974. And it looks like the standard ratio for 1970 was 3.23 while in 1974 it was 2.94.

I think the 240# weight difference is enough for what you describe to make sense, just curious if there were other differences as well.

And the Dart Sport didn't have AC, right? That added over 100#!
they were both strippers: manual steering/brakes. both had 3.23's SG's at the time, the dart sport now has 2.71 for road tripping purposes (along with a borgeson upgrade). i've worked on both cars a fair amount over the last 10+ years, so i'm confident in saying that they're a pretty fair comparison to each other. no flim-flammery or sandbagging, both motors are a about the same spec, carbs are close enough, manifolds and duals. the 340 shines it everywhere. it's not night and day, but enough to notice.