K20 parking brake cable replacement

[1980K20]

Only 50 miles on my rebuilt differential, for some reason I thought it was fine to keep the original cables. They work, but now I have new cables because old stuff always breaks, says Murphy. I know how to install them.

Question on the bearings. When I pull out the drum and axel to get to the cable, all sorts of oil comes out. I raise the side of the truck to limit the drip. Is this just straight differential fluid? I don't need to repack the beatings, do I?

Thanks!
Mark