21 mpg?!?

That is decent MPG for a tired motor, what gear?
I know my first duster with a 318 got worse gas mpg with a od than a straight 4-speed 3.23 gear.


2.76 ...it was originally a 904 but I changed it to an OD to have the manual shift ....with a gear that shallow it takes off pretty weak with the manual, but once its on the highway up to speed then it rides really comfortable.