do I need the front axle in 1999 f150 4x4 to drive it?

 

By "front axle", are you meaning the half-shafts?

We had a Mopar minivan for many years, which was FWD. In the shop manual there was a warning not to try to move the car if either half-shaft assembly was removed, because the hub/bearing assembly may come apart.

When assembled, the outer CV joint's splined shaft passed through the integral hub/bearing, and the hub nut was torqued down on the outer side of the hub/bearing. With the half-shaft removed, and therefore the outer CV joint and nut removed, the hub/bearing assembly was not squeezed together anymore, and could come apart under the weight and stresses of vehicle movement.

I have a first printing of the 1997 F-150 shop manual, and looked up the 4WD front axle, half-shafts, and front suspension sections to see if there was a similar warning. Nowhere was there a warning. But these early manuals have some things omitted from them.
I don't think I would try it unless someone really knows absolutely for-sure that it is safe to do so.

I guess if you had a major half-shaft failure, and couldn't drive it because of that, you could pull the offending half-shaft(s) out, separate off the outer CV joint, and put the outer CV joint back through the hub/bearing and torque the axle nut back to specs.

 

I agree!
How I know...lol
I Removed all my 4X4 stuff.T case,front diff,and axle shafts. But almost had the wheel fall off going down the road.
To solve the problem, I had to reinstall the axle shafts. But did so after cutting everything off after the inside of the hub.
Works great now but the axle shafts DO hold the front assembly together.

 

The inner and outer bearings on the hub must be held tightly together. THe outer nut is about 200 ft pounds on torque. Using the old shaft end thru the two bearings is proper.