'96 T&C, 114K miles, recent brakes, approx. 15K on struts, tranny rebuilt at approx. 90K.

I've had a popping sound from the LEFT front for several months when moving from a stop, or sometimes with a tight turn and forward motion. My son inpected the suspension and said everything was tight except the sway bar links. Ok...no big deal to replace.

Then, as were were cruising around the neighborhood to see how the rear brakes and shocks he had just installed were working....we heard this "CLANK" when I stopped and backed up. Not a little "clunk", but a clear metal to metal "CLANK". Seems to be right side. It does it when I stop, then tap the acellerator lightly in either forward or reverse....both with or without the brake on. We're thinking outer CV joint, but I'd like an opinion before I order the axle.

If it is the axle, can I just replace the one or do I need to do both (is there any mechanical reason to do both)?

It sounds like the axle. If you can inspect it closely, tug on it, try to move it and check the rubber boot. If you need to replace it, just replace whats broken, no need to replace both unless the other side is showing problems.

My experience has shown when you get a noise with accelerator movement it's normally the inner cv joint. Of course if you change the axle you'll change both joints anyway. Some other possibilities would be the upper strut mounts, bad brake pad spring clips, control arm bushings.