well it depends whats leaking?
coming out the drum (axle seal)
or the front where the drive shaft bolts on (pinion seal)
or out the rear cover?
big variations as to where its coming from.
either way the parts are cheap unless your brakes are covered in the oil. and if you know how to fix it then its way cheap.
good luck.
_________________________
Jimmy
81 chev stepside
4.10s locked front
38X12.5X15 swampers