I have a 97 F-150, 4x4, 4.6L. I know the rearend is a 3.55 LS. But is the front diff the same ratio? Thanks in advance. Chris

 

I haven't heard of any weird transfer case split ratios, so I suggest that chances are way better than average that the front has to match the back.

If in doubt, the axle codes should spell it out, assuming the truck still has the stock ratios.

 

If your front ratio does not match your rear you are in deeeeeeeep doo doo. Tire size, ratio, all has to be the same, especialy if you ever put it in 4 low. Every 4x4 will have the same ratio front and rear from the factory. Youur front might not be LS though, you have a H9 axle code?

 

Front never is LS from the factory, and LS in front can be a problem when turning. Vehicle has a tendency to continue to go straight even with wheels turned.
As to the front ratio, yes you have a 3.55 from the factory.