According to the website, if I throw in 4.88's, and drive it to Tucson Arizona,(which is my territory) I'll be doing 75mph(speed limit) at 3600 RPM's. That sounds like a lot for a 2 hour trip



A gear change to any deeper gear will improve the performance and drivability of the EX. Do you currently have the more common 3.73 gears or are you starting out with the optional factory 4.30 gears?
My Ex started out with the 3.73 gears and on pure highway trips it did a best of 15.5 MPG on the stock 265 rubber with my typical mixed daily driving it was seeing 14-ish average tanks. After I swapped in the 4.88 gears I also bumped up from the factory 31.5" tires to 32"s, with that combo it's pure highway mileage dropped to about 12 and change. The towing MPGs (9500lb toyhauler at that time) went from 6/7 MPG up to 9 with the new gears. Later I upgraded to 35" tires (effective ratio of 4.39) and an 11,000lb TT (with custom tunes and banks headers) and am still getting 8 to 9 MPG towing on the highway. The only full tanks I have logged unloaded on the highway in this configuration showed 13 MPG with the cruise set at 65 /70 MPH. At 65 MPH in OD it is turning 2230 RPMs.
Once you finish your regear the next best thing to into is a good set of custom tunes, I went with the forum favorite tuner 5Star Tuning. The changes to the trans performance are well worth the cost of the tunes in my opinion, any actual increases in engine output are just the gravy. [/QUOTE]

 

4.88s and 35s with a ex in OD at 80 mph is about 3000 rpms

 

Well yeah, you will be at 3600 RPMs at 75 MPH in DRIVE but why wouldn't you use OD? In OD you will be spinning at 2460 revs at 75 MPH which is perfectly fine with the V-10, it loves to rev and it is pretty efficient at those higher revs. I have towed our 11k TT in the mountains for 6 hours at 70 to 75 MPH in OD (only dropped down a gear on the biggest hills) and it didn't miss a beat.

 

I'm always in overdrive when I am on the freeway. Maybe I'm not using the website correctly
I guess I was reading it wrong. Overdrive looks like about 2500 rpm's

 

This thread has a lot of pics and covers most of what you need for replacing gears

https://www.ford-trucks.com/forums/1...ferential.html

This article covers anything you'd want to know about setting up gears

http://www.pirate4x4.com/tech/billavista/Gear_Setup/



I burned up the pinion bearings in my rear diff on Tuesday and have a new set of gears, install kit, non-leaking diff cover, and a Truetrac on the way now.

 

Ian does a pretty good job explaining on a sweet '69 scout. ARB locker to boot.


'69 International Scout Part II | Xtreme 4x4 | PowerBlockTV - Full Episodes