ill be replacing my 3rd member this saturday the factroty one is 3.08 the one ill be putting in is a4.11 poss i( i know its a chevy term but cant think of the proper one for ford)ive tried to find the calculaters that people talk aboutfor figuring out the speedometer. i have the T-19 tranny and im running 31x10.5x15 any help as always much apreciated

 

Here is the on-site one.......... MPH RPM Calculator - Ford Trucks

 

For any given speed in any gear, the engine speed will be increased by ~33%.

 

I wouldn't say kissing your gas mileage away, unless you run down the highway a lot, I know in town, my CJ (regeared to 4.10) gets the same or better gas mileage, I turn 35's on it and it is more efficient from stop light to stop light while grocery getting, less reving the engine and it gets in it power band quicker and stays there. Particularly if your planning on going to any larger tires.

 

You're right, the term "posi" was used by GM, but I see that now it's also used by Eaton for an aftermarket limited slip (I don't know if all of the GM posis were from Eaton or not). The generic term is limited slip (applies to all makes), or more specifically, clutch-type limited slip (to not include the gear-type limited slips like the Truetrac which is completely different). And for what it's worth, Ford's term for the limited slip they used is TracLoc (not sure of the spelling, I've seen it with and without one or more of the "K"s)

 

thanks for the input and replies

 

You may be pleasantly surprised about what happens to the gas milage, if you do a lot of highway miles you may lose a bit but all you go to do to get that back is swap in a 5-sp trans.

 

4.10s and no OD is going to suck with only 31's

Plan on about 2500 at 55.

Personally I would of done 3.55 or 3.73 since you have such a small tire and no OD

Also, are you SURE you have a T-19?

 

diesel brad i would have love to have the lower gears but the rearend was going fast i needed something fast my friend had a set between paydays and on credit i took him up on it i didnt know the gear ratio untill i got to another buddies house and discovered its not just a 4.11 but a true lock im sure its t-19

 

Then sell the 4.10s and get 3.55 or 3.73

Who put the T-19 in?

 

i put it in i couldnt get the cheesy linkage for the original 3speed to work with out jamming and i got the 4speed with the truck so i put it in