front axle you must unscrew the bottom most axle housing to 3rd member bolt to drain...put goop sealant on bolt then put back on and tighten with a small wratchet or you could torque them off. Then use 24 MM socket to unscrew fill bolt and then pump untill gear oil starts to come out.

Rear you undo the drain bolt then use goop sealant and take CARE when tightening back on..use a 3/8" or 1/4" drive as not to overtighten...I once used a 1/2" drive Snapon wratchet and tightened the drain bolt and pop!!! twisted it out...I had to go get a bigger tap and thread and use a bigger bolt. Then same as front ...fill untill gear oil comes out fill bolt and then tighten...make sure you use torque seal and do not over or under tighten or you might lose your bolts and gear oil will sling out when driving.