ranger px1 automatic 3,2

G'day Barry.
I haven't looked closely at the ranger transfer case but, if it is engineered as most others, the front shaft can be unbolted, the nut on the Uni yoke flange can be held and the but loosened and removed.
That should leave the seal presented so it can be prised out and a new one fitted.
Also check the wear ring path where the seal lip runs as it may be damaged and the new seal not last long. If so, a "speedie sleeve" may be the answer there, or some other remedy to refresh the boss area of the yoke.

Check to see if the breather is clear, as a blocked breather create increased seal lip pressure and wear rate if pressure is allowed to build up as it gets hot while running.
When replacing the front yoke, some method of sealing the splines is needed so oil doesn't wick out along the splines and through the nut threads to the outside.
Some have a thin O ring inside or sealant used at the end of the yoke face when fitting. Loctite 518 maybe.

Under an hour would be my estimate if no additional wear lip issues are present.

Barry - RMD has nailed it. This is a reasonably common fault with the Ranger/Mazda BT-50 transfer cases.

Note in the discussion link below, the standard Ford transfer case front output shaft bearing has 9 balls - the heavy duty replacement bearing has 13 balls.
More balls in a bearing means more load capacity and longer life.

Ford are mongrels for continually cutting costs by using cheaper parts, they have done this for decades.
A cheap bearing with a reduced number of balls develops "slop" over time, and this chops out the seal.

Add in mud, dirt, water, and dust getting thrown at it by the front wheels, in combination with "slop", and you end up with a short life for the seal.

Transfer case front seal - Ranger

Cheers, Ron.