85 Tercel 4x4 needs front diff change info

Hi all:
need some info as what to do. Picked up a 85 Tercel 4x4 auto.
The guy sold it to me for real reas price, as front diff is gone.
My mech told me my front diff crown & pinion were both gone.
My Mechanic not real familiar with these machine. Now the big Q. is what is the easiest way of changing the front diff without resorting to dropping the whole transaxle. i have seen it in junk yard where the front diff was sold separated and gone. So is there a way of taking the front diff apart w/o dropping the tranny or thats the way? Please email to [email protected]
TIA.