Rear axle lost grease now noisy

[4gfun]

I lost the metal clip that goes to the rear driver's side axle (circled red area of someone elses car). I put a large tie wrap on there so I could get to work.

I had every intention of putting a worm clamp in it's place but forgot to do so.

I was driving my car at low speeds the other day and I heard grinding like a stuck rotor. I noticed axle grease all over the rear diff and under carriage.

I can't verify the noise since it comes and goes but I am obviously suspicious that this is the problem.

The questions are:

1) Is it too late to add grease to the axle?

2) Is it possible or practical just to service that axle?

3) When servicing that axle, will I lose the redline shockproof I put in the rear pumpkin?

4) Do the noises I mention sound like an axle issue?

Thanks for any help, I don't know anything about the rear axle setup (e.g. what each part is called etc) so I came here. I can tell you that this is a 3 bolt if that helps.