My truck has the 3.73 RATIO REGULAR AXLE. What does this mean?

 

Ratio of how many times the drive shaft turns to how many times the axle turns.

In other words your drive shaft turns 3.73 times every times your axle turns.

It also means you have an open differential.

 

what is an open differential?


what is the 3.73 gears good for?

 

In general higher ratios are better for starting line take-offs and towing and worse for MPG.

http://www.google.com/search?q=Open+...x=&startPage=1

 

the 3.73 is a good all around gear for a stock truck with stock or slightly larger tires, for towing. Good take-off, and decent fuel economy.

The higher the gear ratio number, (ie. 3.73) the lower the gear ratio. A 3.55 for example will have a little less acceleration, tow a little less, but be turning at a lower RPM at highway speeds for fuel economy.

Almost all f150s come with 3.73s or 3.55's. sometimes you'll see 3.31's, but that's too high for most purposes. 4.10's are available in the f150 HD's.

The "OPEN" differential means you don't have a limited slip differential, so only one wheel will get power if you get stuck. On dry roads, you'll never know the difference, but if you go off-road, or drive in dirt or snow, you will.

 

I have a 2004 f150 extended cab xl 4x4 with a 9in rear end.. how do i find out wheather it has 3.55 gears or 3.73 gears

 

the sticker on the driver's doorjamb will have an axle code. you can find online tables and what not to tell you which axle is which code.