Found that the knocking I was having is coming from the rear differential.
Haven't removed the cover yet to see exactly what the problem is.
How involved is it to repair any parts that need to be replaced?

 

Depends on which parts need to be replaced..... If you pull the ring and pinion gears, you need a selection of precision measuring tools to put it back together right. (tolerances measured in thousandths of an inch.....) If you have a buddy that has done gears before, that would certainly help.

 

It isn't hard, but does take some specialized tools if you're gonna change bearings or even just take the diff. out. Carrier and pinion bearing preloads need to be properly set and backlash needs to be set.

 

As HeyYou said it's rather involved, having a shop do the work is expensive as well.

Take off the diff cover, post a pic.

 

^as said, take a close look. replacement of spider gears or side gears is easy. ring and pinion is very detailed.