if it is a 4.0 it is an 8.8. unfortunately the ranger 8.8 is several inches to narrow for a cherokee and also a 28 spline version.
if i am not mistaken, the 7.5 and ranger 8.8 even use the same axle shafts, have the same weight capacity along with the same pinon and axle bearings. the only increase in strength is the ring gear and carrier bearings.
it still won't fit in a chero though.