Need idea of cost for rear end build

[dwcopple]

Okay, so actually after doing a TON of reading on various mustang sites, I'm thinking 4.10 might be better with my 4r70w auto. The car is just my toy and gets less than 3K miles a year on it. I think the massive torque & acceleration gains are probably worth it. Anyone have this setup and can tell me cruising RPMs at 75mph?

 

[TrickVert]

I've seen 4.10's recommended for auto-equipped Mustangs almost exclusively. Here's your RPM calculator: https://www.cjponyparts.com/resources/engine-rpm-calculator

 

[dwcopple]

Yeah. I'm going 4.10 if I get FRPP gears and 3.90 if I get motives

 

[Wmac]

I have a 95 with an aode trans and 4.10 gears. At 60 mph it revs about 2250 rpm in 4th gear. (stock tire od) So the calculator provided above is "close" to my actual. The gear set from a 4r70w trans would put me in the 2400 rpm range at 60. At 75mph, it would rev about 2800 rpm. That's buzzing it at a sustained highway speed.

Its long been said for an aode use 4.10's and for a 4r70w use 3.73 gears.
If the op runs any #'s at the track, he could expect his 4r70w to run through the traps at about 55 to 5600 in 3rd gear with a 4.10 gear.

His 60' time would be so much better that mine are with his gearset.

 

[dwcopple]

So, does my 98 need a speedo gear or will my SCT X4 fix it?

 

[RAU03MACH]

So, does my 98 need a speedo gear or will my SCT X4 fix it?

When I did my 373 on my 98 with automatic
I changed out the plastic gear
I was told by ford they really don't have a
Tune fix for the speedo

 

[RAU03MACH]

But keep in mind I did mine in 2013
Things can change

 

[dwcopple]

I have an SCT, does it only work on 99+ to recalibrate?

 

[RAU03MACH]

Not really sure
Another way to tell look at the transmission where the speed cable goes
If cable is there than use a plastic speed gear
If its a wire harness than use your programmer