I did a mileage test in my Duster 340/4 speed and it did 19 MPG (even with hammering it a couple times & opening the 4 BBLS).
When I had my '79 Volare with slant 6, I used to get 28 highway and 22-24 city.
Was that with a 833 O/D or with a 904?? If with a 904 I'm just gonna get the aspen that I bought last night running and drive it!! My 89 s10 with a 2.8 non O/D 5 speed only gets 22-23 highway!!