Need New CV Joints - How to tell if wornout and need replacing vs repacking greese

[Tidybuoy]

My transmission has recently started making a howling noise coming from the passenger side. When looking over things, I noticed that the CV Boot has a large tear. The noise is not always there but I can make it re-occur if I lug the engine a little (i.e., 5th gear at 35mph). There's no clicking sound that you usually get with cv joints. Also, I recently changed the gear oil and it is ful (swepco 201 which is what was previously in there).

A Few Questions:

How can I tell if the cv joing needs replacing vs. removing, cleaning, repacking, and new dust covers.

How can I tell which CV joint for my '74. The PET has numerous part numbers and Pelican shows (74-mid 75) and (Jan 75 thru 84). it seems that if option 1 fits thru mid '75, then option 2 is the same.

Is it possible to see the part number before removing - I'd like to order what I need before taking everything apart.

I'm open to advice.....Thanks.