Hello. I have a FX4 that I bought new in 2003. It now has 54k miles and runs great. Never anything done to it, other the the Lin-X bed liner. All Fords in the family; 03 Ranger, 06 F-150, '12 mustang GT, and '16 Edge. All are great cars, and I wouldn't have any other brand. The Ranger has a 5 spd manual trans and I would like to lower the RPM's at hwy speed, so if anyone has any suggestions to improve (i.e., lower) the RPM's when in overdrive, let me know. The truck came with a 4.10 rear end and I would like to keep it; only lower the overdrive ratio.

 

Welcome to the forum

Nice Ranger you have there

No simple way to change M5OD-R1 transmission's OD ratio

Taller tires lowers ratio same as changing front and rear differentials to 3.73's

4.10 is a trailer pulling option normally but came standard on the FX4s for better off-road ratios, lower 4low

For 2WDs you can use under/over drive also called gear splitter box on output shaft, so changes a 5-speed trans into a 10 speed trans
And I guess you could use that on 4WD as long as you had added gear box in "normal" position when using 4WD
Google: gear splitter

Now you could put gear splitter between trans and transfer case, similar to what off-roaders do when they use two transfer cases, they want lower crawling speed.
Certainly doable, but not cheap