1973 Dart Swinger

erafuse said
View attachment 1715357607 so probably a 7.25. Any ideas on how to improve gas mileage. 318 2v Auto.

Yep 7.25.
I put an A500 overdrive out of a Dakota pickup in mine and built an automatic shifting system for OD and lockup.
If you are doing 19-20mpg you are doing better than most already.
Getting those hiway RPM's down is the key.