Any one know a way I can decode my VIN to find out if I have an LS rear or a Std Rear? and what the ratios are?

If its an Open rear Im going to be putting an Air locker in front and rear along with a R&P Change to recover some of the power lost due to my 35" tires.

 

Check your diff cover for a metal tag. The tag will tell you if you have an ls or not. Or you can use the tag in your drivers door jam.

19 — 3.55 non-limited slip — F-150
25 — 4.10 non-limited slip — F-150
26 — 3.73 non-limited slip — F-150/Mark LT
27 — 3.31 non-limited slip — F-150
B5 — 4.10 limited slip — F-150
B6 — 3.73 limited slip — F-150/Mark LT
H9 — 3.55 limited slip — F-150

 

Open the drivers door and look at the sticker...there is an axle code on it..B6... 373 LS H9 .. 355 LS

 

Thank you!

B6 3.7 w/LS going to a 4.10 w/o Air lock. Maydo Air Lock up front however

 

You won't see much gain going to a 4.10 from a 3.73, you should consider 4.56 gears.

 

X2

 

4.56 is a little low for what I want.

Im going for just stock power feeling.

Stock tires = 32.1"
New tires = 34.5"
Stock Gears = 3.73:1

(new tire/old tire)*Stock Gears = New Gears

(34.5/32.1)*3.73 = 4.01:1

So 4.56 would be a little way to low. Much of my travel is high way and mountain highway so I want the acceleration and pulling of stock without being so low that I'm wrapped out on the at full speed.

 

How do I know what ring size my truck has? I want to get a new cover for it also. There seams to be 3 options

 

It should be a 9.75, assuming you have a 5.4l. The tag on the metal tag on the diff cover will tell you what you have. It will look something like this, 9 75 3 L 73. The 9.75 is your ring gear size, and the 3 L 73 means; limited slip 3.73.

 

Yes, at the top of the forum there is a sticky: https://www.f150forum.com/f4/get-fre...ticker-124846/

You can see the ratio/axle info here: http://services.forddirect.fordvehic...MF1CM1DKF30217