Rear Axle Bearings need Replacement?

[newbraunie]

I am in the middle of R&R of rear brakes on my 69 C-10. I noticed that when I turn the axle the bearings make a very squeaky noise(s). They sound as if they are not being lubed. I also drained the differential and do not know if it was low prior to draining. I guess I could measure the amount of fluid that came out. It does this on both sides. There is no play in the axle shaft or seal leakage. I am wondering if I should repalce the seals and bearings? Other than the squeaky noises the bearings make there is no other indications that I need to replace. Any advice out there guys?