that depends on the ratio you are looking for. example- if you happen to be looking at 4.56 gears. look for cucv axles. that way the gears are already done and the rear will already be locked. if you want 4.10s look for front from a 1 ton, and a rear from a 3/4 ton. thats a common factory ratio and that way both axles will bolt in. a 1 ton rear will need shock and perch mods to fit.
if you want lower like 4.88-5.38s. i would find the cheapest axles you could find. then overhaul them to your specs.
initial purchase and a comlete overhaul for a 60 front can be more than $3k
a 14 bolt up to $1500.
thats with labor. doing the work yourself can really cut the bill down. im into my 60 about $2400. my 14 bolt about $750. thats complete overhaul including brakes. but not steering. doing all the work myself.