ball joints - upper/lower? how to tell?

My mechanic says my upper RH ball joint (4wd so full control arm), must be replaced. Have read the other ball joint thread and parts sourcing issue so am aware of the concerns there.

I jacked the car and did the top to bottom wiggle test and it clicks and feels loose so this confirms his claim.

*4wd with a 2" lift

QUESTIONS
- how do I know it is the top ball joint that needs to be replaced and not the bottom - do I just replace both to be safe or should I do bottom and then re-test?
- the LH one actually feels like it has the same amount of play at RH, wondering why he did not call this one out as well - should I just get both done to be safe?
- How much more effort is the LH vs the RH one to get done, assume radiator comes out for both etc.

Thanks.

In order to check them properly you have to jack up the van and put it on stands, then with a crowbar under the tire lift the tire up and down, while watching the balljoints, wiggling that same wheel side to side will indicate play in the steering linkage (and BJ's if really bad)
The lower ball joint is about 8in away from the upper joint so if you are looking at the joints it should be rather clear what you need to replace.

Bear in mind, 99% of shops out there are completely unaware that the upper balljoint is allowed some play, as per the manual:
"Maximum vertical play = 2.3mm"'

Most shops will assume the standard of "zero play" and automatically condemn a "good" joint.
Replace what is needed, but do it in pairs (both uppers, both lowers...)

wow - missed the 2.3mm play. I see that in the manual now and will point it out to my mechanic. Could be a $1000 save right there ;)

Thank you!