the only way to gain more diff clearance is taller tyres,for every 1" taller you will gain 1/2" under the diffs,there are different ways of fitting taller tyres with pros and cons for all of them.

you can do
body lift
pros leaves the heavy parts lower down and is cheap
cons can be hard to do and does not help with aproch/departure or breakover angle

spring lift
pros improves aproch/departure and breakover angle and can give more flex
cons cost

shackle lift
pros cheap improves aproch/breakover angle
cons they can bend springs reduce departure angle and upset your steering

spring over axle
pros gives a lot more flex and improves aproch/departure and breakover angle
cons cost lifts your truck too high so will be easier to fall over

virtual lift
pros keeps the waight low
cons will need to cut and weld your arches does nothing to improve aproch/departure and breakover angle

for any one who does not know what a virtual lift is it is when you cut you arches back far enough to fit bigger tyres without doing a suspension/body lift

there maybe more pros/cons for all of above but hope this helps parrot