There is a spray of grease (green, looks like chassis grease) radiating out from my left side drive shaft. It lines up with the inner clamp on the inner boot (inner + closer to trans). I pulled the wheel yesterday and rotated the assembly to examine the boot, and there are no breaks or tears, and the clamp is firmly seated.

What am I missing here?

Could be a small hole. I would wipe the grease up and then keep an eye on it.

I've seen the boots leak on full pegged turns etc. Sometimes from the clamp area as the boot flexes to it'* limits.

I'd run it til you know the axle is bad, then swap.

I might just swap it now. Better to do it now when the weather is okay rather than in the dead of winter. Also, I need new tires and I want to get an alignment. If I replace the axle before the tires I won't mess up the alignment.

What are the signs of a bad axle (other than leaking grease)?

In Dan'* write up (https://www.gmforum.com/mechanical-134/axel-replacement-94-bonneville-se-296711/) I am a little confused over the description "push it as far in as you can to release the lock ring and it should pull right out..you may have to get behind it and pry a little". Does that mean pushing the half shaft toward the trans will release some sort of lock ring? If pushing releases the lock ring, how does prying it away from the trans aid in releasing it? Where is this lock ring, and how do you release it?

nothing too technical just a ring to keep the axle from coming loose under normal conditions, just grab a hold of the axle and pull it out

No no, don't just grab the axle and pull. You risk messing it up, not that that matters if the axle is going to be replaced. But as a matter of habit, don't pull it that way. There'* a small ring that can lock in place. When you push it in towards the transmission, it will unjam and give you a little bit of movement, and that'* needed to pop the ring. I have a wide pry bar that would be used for pulling nails out of wood. Perhaps 2 inches wide and a foot or so long. 90* angle on one side and a small curve on the other. Push the axle in all the way, get the pry bar behind it and give it a sharp snap and the axle should pop right out. You may need to do it a few times, but it will pop right out.

The compression clip that holds them together will not release if you pull directly and put constant pressure on it. That'* how it'* designed to hold.

Therefore push the axle in all the way, then quickly (from behind the inner CV joint) give it a quick pull or tap from behind. This quickly jabs the compression ring into the compressed position and releases the axle.

FWIW if you pop the balljoint, you don't disturb alignment.

Thanks for the insight.

Bill, I agree this won't mess up the alignment. My main reason for doing it now is I know it will fail in the near future, and my luck it will be in the dead of winter. I would much rather anticipate the failure and fix it while the weather is perfect for working on cars.

What, don't like working on the car when it'* 20 below?

I'm too old for that $hit.