Rear control arm clunk?

[Jagernauth, Stephen, RTLSL]

Guys,

I've been living with an annoying clunk in the rear suspension for some time
and I'm looking to fix it.   I can't feel any play in the wheel but when I had the car
inspected, they failed it for bad right rear control arm.  Is there a test to ensure this is the
culprit?  There is nothing visibly wrong that I can tell but I hate to change parts blindly.
Can anyone BTDT share their experience, I assume I would need an alignment after.
Any special tools?

I'm pricing it from Performance Motor Cars which has
had great prices and no shipping charges for orders over $50.  It is $99.

http://www.performancemotorcars.com/

p.s. I just finished installing an engine in my track car so I have a lot
of mechanical experience, just don't trust the local monkey wrenches.

Steve Jagernauth
'91 200 20V black
'74 911 3.2 coupe
'74 911 3.0 targa