John,
Rear end number is the ratio of the ring gear teeth to the driven gear teeth (pinion or drive shaft in this case). That ratio is applied to whatever speed the drive shaft is turning regardless of the gear the transmission is in. The transmission is before the rear end and changes in gears there change the speed of the drive shaft. And the rear end just passes that on to the rear axle at the ratio of the teeth. So no matter what gear you are in the rear end ratio is applied the same to all gears.
A 4.10 rear end just means there are 4.1 times as many teeth on the ring gear than the pinion. More teeth on the ring gear (bigger number) means the rear axle will turn slower before it makes a full revolution.
But you are right, if you have the rig on all the time and are in mountains a lot and on back roads a lot and/or towing, the 4.10 rear end will do great.
Reply To: ? for F 250 owners – options mods etc on custom ordered 2019
