Daily drivers, I have 2 that have D/D status. 1st: a 69 F-250 2WD, 390 C6, D-60 3.73 gears, stock lower end, cast flat top pistons, log ex. manifolds, D2 heads with SS valves, 2.09/1.65, hyd cam in the 270 deg range [I can't remember the exact specs as I built this engine in 1991] Stock iron "S" manifold, 600 cfm Holley and stock dist. with some tweaking of the advance curve. Runs good on Calif. 89 octane and gets 12.5-13 mpg. 2nd: 66 Fairlane GTA, 390, C6, 9" w/3.00 gears. Stock lower end, cast dish pistons, C6AE- 14 bolt heads, stock GT exhaust manifolds, SS valves 2.09/1.65, Hyd Crane cam 272/284, Edel. Streetmaster, 600 CFM, stock dist. and the usual advance tweaking, also runs good on Ca. 89 octane and gets 16-17 mpg hiway. A 3rd that is not exactly a DD anymore. 66 Galaxie, 428, C6, 9 3/8" 2.75 gear. Stock lower end, cast dish pistons. log manifolds, C1AE heads, 2.09/1.65, old 406 solid lifter cam 276/.479" Ford C7 P/I aluminum manifold, 600 Holley, stock dist. and the usual tweaking of the advance curve. Also runs ok on 89 octane with occasional 91oct. and gets 15.5-16 mpg hiway. All 3 have decent street mannners, dead nuts reliable and fuel mileage I can live with. It would be nice to get better fuel mileage, say 20 mpg but it just isn't happening with 50- 60 year old technology, big heavy cars/trucks and with an occasional heavy foot.