[06SatinSilverV6]

i am thinking of doing a trac-lok diff on my 7.5" rear in my v6. my whole thing is if im gonna be in there anyway why dont i just do gears too. im pretty sure that the stock gt's come with 3.55's and the stock six's come with 3.31's, if im wrong please somebody correct me. anyways, i want to maintain the ability of highway economy still but make it a little faster out of the hole and more fun. the problem im having is that i was thinking that 3.55's would be the best, but i can't seem to find a 3.55 gearset for a 7.5" rear. anybody else have this problem too or know where i can find them. 3.55's for an 8.8 is very common. thanks!

[fishingjts]

Originally Posted by 06SatinSilverV6

i am thinking of doing a trac-lok diff on my 7.5" rear in my v6. my whole thing is if im gonna be in there anyway why dont i just do gears too. im pretty sure that the stock gt's come with 3.55's and the stock six's come with 3.31's, if im wrong please somebody correct me. anyways, i want to maintain the ability of highway economy still but make it a little faster out of the hole and more fun. the problem im having is that i was thinking that 3.55's would be the best, but i can't seem to find a 3.55 gearset for a 7.5" rear. anybody else have this problem too or know where i can find them. 3.55's for an 8.8 is very common. thanks!

There are no 3.55's for the 7.5... you'll need to go up to the 3.73s...

[SOHCman]

Originally Posted by fishingjts

There are no 3.55's for the 7.5... you'll need to go up to the 3.73s...

Hi folks,

Been looking around for gears as well.

The 7.5" axle can accept:

3.08
3.27
3.31 (stock 05-07)
3.45
3.73
4.10 (*?)
4.11 *
4.56 *

The 4.11 & 4.56 gears need that "notched X pin" that everyone sees in the online catalogs.

These guys have the biggest selection.
http://www.jawsgear.com/store/catalo...products_id=66

These guys have only Richmond gears:
3.45
3.73
4.10
http://www.rearendparts.com/xcart/ca...-p-1-c-55.html

More info from http://www.drivetrain.com/ford7.5.html
Part # OEM # Teeth Ratio
F7.5-308 M4209L308 37-12 3.08
F7.5-327 M4209F327 36-11 3.27
F7.5-345 M4209L345 38-11 3.45
F7.5-373* M4209L373 41-11 3.73
F7.5-410* M4209L410 41-10 4.1
Requires cross shaft E4SZ4211A (will not fit Auburn Carrier)

The 7.5 axle has been used for years in other Ford vehicles.

The ratios are out there if you look hard enough.

Looks like we're not so limited as we thought.

Have fun!

SOHC

[iceman320]

couldn't you use your stock ring gear and put it on the t-lok unit?

[wally05]

Originally Posted by 06SatinSilverV6

i am thinking of doing a trac-lok diff on my 7.5" rear in my v6. my whole thing is if im gonna be in there anyway why dont i just do gears too. im pretty sure that the stock gt's come with 3.55's and the stock six's come with 3.31's, if im wrong please somebody correct me. anyways, i want to maintain the ability of highway economy still but make it a little faster out of the hole and more fun. the problem im having is that i was thinking that 3.55's would be the best, but i can't seem to find a 3.55 gearset for a 7.5" rear. anybody else have this problem too or know where i can find them. 3.55's for an 8.8 is very common. thanks!

From my understanding, you won't lose a lot of gas mileage with 3.73's. If you have the intake/tune combo, you may not lose much at all.

[SOHCman]

Originally Posted by iceman320

couldn't you use your stock ring gear and put it on the t-lok unit?

I am keeping the stock 3.31 gears.

I do 90% highway driving so I can't afford to make mileage worse.

SOHC

[06SatinSilverV6]

i didnt know you cant get 3.55's for a 7.5. do all you guys think that 3.73's would really affect fuel economy versus 3.31's. also given a cruising speed such as on the highway, how much higher will the rpm's be witht he lower gears?

[Chrome Cavalry]

What are the best gears for racing thru the power band to the next gear change, allowing you to turn the power on earlier?? What Diff do you best compliment this with? WHat driveshaft should you consider too??

I am quite happy to sacrifice top end speed for smoothness and less time getting to top speed. Over here, over 100MPH and its a dangerous driving charge and a ban. So I don't need 150MPh, I'd settle for 110.

Any ideas, and how much can I expect to pay??