you have 3.08 gears, a 4R70W transmission. I can't find the final drive ratio on that transmission, but I'll just say in 3rd gear at 1:1 trans ratio, going 60 mph you are at around 1700 RPM with of course a 3.08:1 ratio.

A 6 cyl needs to run in between 2000-3000 at highway speed (not in OD).

With 4.56 gears at 1:1 (3rd) you should be just above stock feeling and around 2600 RPM at 60 mph and around 1800 overdrive rpm, so either 4.10's or 4.56's would be best depending on what you want, 4.10's will give better fuel mileage while 4.56's will have a bit more pulling power.

 

Does anyone here run the 4:30 gear or have any experience with it. That may be right in the middle. I want it to help my gas mileage and give it more pep but dont want to be wound out on the highway at 70mph.

 

Never heard of a 4.30 ratio, but that would put you in the best of both, power and fuel mileage. With either ratio you won't be "wound out" at 70 mph, it will be just like it was with stock tires.

 

So the 4:56 will be like it was before putting my tires on? I dont want to spend my money twice I just want it to pull atleast like it did before. Its a dog now it shifts down going up the smallest hills and I cant think about pulling out in traffic.

 

The 4.56's should have a tad more power than it did when stock, not sure what tires you are running but as long as their not a heavy tire (i.e. bogger's) then it will be perfect IMO.
I wouldn't go above 4.56's unless you want to watch your gas guage drop fast every trip.

 

Thanks for your help on this. I am running Dick Cepek FC II radials by Mickey Thompson 35's. I surely cant afford to watch my gas gauge fall any faster than it does already It is a huge difference from stock tires.

 

No problem, glad I could help. Give Motor haven or Randy's Ring & Pinon a call, Randy's gave me a great price when I bought my 5.13's. And since then I have bought all my gears, axles and lockers from them. EXT. 5571 is the guy that I deal with.

 

I have 35s on my 02 FX4, stock 3.55 gears. Adding the 35s lowered the ratio to about a 3.25gear ratio. I am getting ready to put a set of 4.10 gears on the truck. My truck does the same thing, just alittle sluggish with the bigger tires. 4.10 gears with 35s will be the equivalent to 3.73s which is a good well rounded gear for mileage, power, and towing.

 

Well I ordered my 4:56 gears today I will update once they are installed. Thanks johnsonswamp, cleevesj and everyone else who helped with my decision. I cant wait to see how it changes my truck

 

johnsonswamp... You gave me some great advise the 4:56's went in yesterday and it made my truck a whole new animal I am so glad I didnt go with anything else my truck pulls like a beast now and doesnt constantly downshift anymore. I really appreciatte the input on this

 

That's great news! Glad that I could help. Have fun an enjoy your truck again, need anymore help just pm me.

 

TinyG F150...what kind of RPMs are you turning now going to 4.56s? For Ex: at 55,65,75mph, whats your RPM? Debating 4.56s on my 02 FX4 5.4L with 35s after alot of you opting this route, sounds like everyone is happy with them. I have stock 3.55s and was gonna go 4.10s...maybe 4.56s is a better choice. I was just worried about my motor winding too high for a daily driver.

 

My speedometer is pretty bad off but running along with traffic on I-24 ( usually around 75-80mph) Im running around 2200-2500 rpms. I had the same concerns about 4:56's winding out being an old Stang guy 4:56's sounded crazy but I am so glad I went with these gears. My truck had 3:05 gears so the difference will not be quite as drastic on yours going from 3;55's.

 

Thanks TinyG...I keep going back and forth between thinking 4.10s to 4.56s...sounds like everyone thinks 4.56 is the way to go!

 

I am also running 4.56's with a 5 speed manual and 36" tires. I am running about 2700-2800 rpm @ 75mph.