sm.mcnair

I have a Dana 30 axle I'm swapping onto my XJ, and while prepping it noticed its got:

1) a cracked slinger (the plastic one shown in the link below)

http://www.jeep4x4center.com/slinger...c-4882135.html

which goes on the axle shaft and kind of slides into the tube, behind the knuckle, as shown by part number 23 here

http://www.jeep4x4center.com/jeep-ax...herokee-xj.htm

2) a bent dust cover that goes behind the brake rotor, on the same side.

Is it worth replacing EITHER of these parts? if so, can anyone direct me to a good break-down on how?

thanks in advance