Hello all, I had some questions in regards to overdrives and rear end gear ratio. I have a 56 F-100 with an inline 6 and a factory Borg Warner overdrive. The truck has factory 4.09 rear end ratio and a pretty small tire (I can't remember the size off hand). The OD works but even with it at 65 the truck "feels" tapped out. I am doing a lot of upgrades this winter, lowering it and such. I am going to swap in an early F100 9", and have a 3.50 gear set and a 3.89 gear set. I am not sure what tire size I will choose, because I am not sure if I will 15" or 16" wheels, but I feel it will probably be an 8.00 15 or like a 7.00 16. I may leave the 6 or eventually upgrade to a mild 292 V8. I know there are a lot of variables in my math equation, but based on this loose info, I am guessing the 3.89 gear set would probably be the wiser choice? Truck won't haul much, but I would like to do 60-70 with ease. I don't want to gear it too high, it is a heavy truck. I have a 53 sunliner with 3.90 gears and non overdrive and the flathead pulls that car 65-70 pretty easy. But, do any of you think the 3.50's may be a better fit?