So, something in the back is ticking.

It only seems to happen over 30mph, and when going up/down hill and
turning slightly.

It just started this past weekend, so hopefully I still have time to do
something to fix it and not have to replace everything with new parts.

I crawled under the van a moment ago, but all of the boots look perfect.
The 'outer' passenger side one looks sorta scrunched up tighter than the
others, is that a sign of it starting to fail?

The 'outer' drivers side one has some fresh-ish-looking grease in the
little trailing arm thing (whatever you call that box the CV is hidden
inside of.) - Perhaps that's the culprit?

If all the boots look ok, should I just service all 4 of them now and be
done with it? or is there some way to tell which is the bad one, so I
can just service and/or replace that one?

this is for my 81 westy.

thanks,
chris