Thanks softconsult and Icefire. You both mentioned CV joint. Today luck was on my side (well lucky finding the problem
, but not so lucky finding out that the problem is the CV joint
). Drove out 10 miles then headed back 10 miles to my mechanic and the noise started just 1 block from his shop
Mechanic says CV Joints. Lots of threads recommend CVJ reman half axles. Mechanic said buy them and he'll put them in. Just did: $142 + $50 core each + shipping ($20 total shipping estimate).