03' F-150 Front Axle Shift Fork Replacement

Is it possible to remove/replace the shift fork and collar in the front diff with out removing the entire front axle assy?  It looks possible according to the drawings from the parts dept computer at my local Ford dealer.  It looks as if the passenger side axle tube unbolts from the CV side and the diff housing as well allowing the axle tube to slide out gaining access to the fork collar assy.  If so, how much 90wt oil/fluid can I expect to lose?  I would think having the truck on the ground instead of having the suspension hanging from jack stands putting down pressure on the CV is the way to approach this?  The vacuum actuator/t-case is functioning, but there is no front wheels engagement when 4x4 is selected.  Thanks!