It'll be interesting to see if it works out that way. It may have just been a function of my tired 360, but no combo I ran netted better mileage at 65-70mph. Thtottle position plays in to how much air/fuel is getting in to the engine, so I think the lower mechanical advantage of the OD was forcing a deeper throttle and drop in potential mileage. The joys of driving a brick...

Clair