Not really hard.., more like technical, proper proceedure & order. (prob. a 3-4 banana job)
Ea. axle could take a day or two. (Go to local library to bone up)
Especially the front.., you have to remove everything right down to the knuckle. The bug-a-boo is,
you have to inspect every single part for ware so as not to have to go back in again for another
repair. i.e. bearings, knuckle ball joints, spindles, hubs, axles & axle u-joints, seals, etc.
There's a few levels of differential service kits.., depending on whats worn in there.
Kits have shims, white gear teeth coating, etc. so as to get the proper gear to gear contact.
(This prevents howling)
The rear is a bit easier..., but several proper proceedures as well.
Stop at your local "Driveline Shop" & ask for some tips..!!
You may decide to let them do it.