Overdrive options

famous bob said
how could the driveshaft be still spinning at the before rpm, when the final drive out of the trans is reduced , slowing everything down ??? lost me there !

The gearing in the trans and OD have no bearing, if the pinion was spinning at "X" rpm at 75mph with say, 4.56 gears, then the shaft is STILL spinning that fast with an OD in front of it

roccodart440 said
Must be why my cummins ram has a double OD and 4.10 gears from the factory and 258k miles.

This theory has been brought up before and dispelled by numerous professionals in the business.

And that myth has NOT been dispelled, and I'm not talking about paltry 4.11's. You get up into 4.89--5x ratios and start spinning them long distances down the highway at 75mph, you are eventually going to have a problem. I'm talking about passenger cars with typical "short" tires. Your pickup is an exception due to large tires. My 2500 is 4.10, it runs just over 3K at 70mph (with OD locked out). That is not a problem.