I tried diffrent gear ratios over the years to find the sweet spot , my early pintos with the 2.0 4speed and 3.55 gears I felt that there was a need for a 5th gear on the hwy , my pinto has the V-6 built up for torque and a A4LD overdrive trans , I have 15 wheels with 205 /60 /15s , and a posa unit with 3.55 gears , in over drive my rpm is 2500 at 70 mph , 2200 rpm its 60 mph and touching 30 mpg , it has TBI fuel injection , a 2.9 crank out of a bronco ii , and long tube headers , comp cam , I pull a small camper with it that when full up is 2400 lbs , I do not pull in over drive , but in drive only the the converter locked uped , yep around 3000 rpm a tad below 65 mph , it pull hills like a truck ,