would the vac line be on the front axle itself

 

This gen of trucks 97-03 are all vac disconnect on the front axle. there will be to lines running from the actuator up to the pass side fire wall

 

thanks but would it hurt if i bought the wrong axle. I know its a 3.55 one is $100 cheaper than the other

 

The gear ratios much be the same if you want to use 4x4

 

the one we are looking at is a 3.55 also out of a 99 F150

 

All 97-03 F150s have selectable four wheel drive. Some 97-02 Expeditions use selectable four wheel drive and others have full time four wheel drive. If its selectable then you need the axle with the vacuum actuator.

You will want your front and rear axle gear ratios to match in order to avoid binding when the tires are spinning at different speeds.

The swap is very straight forward. Just make sure to spray the bolts down in advance as they can be pretty stubborn to get loose.