l do not think it is the cv shaft. l put the car in park and get out and grab the tire and rock the van back and forth l get one click and thats it, if it was the cv shaft it keep clicking. what is on the other side of the cv shaft.
l has been doing it for about 80,000 miles but has gotten nosier in the last 8,000 or so. can you get in to the trans and fix it with out haveing to pullthe trans out ,but with 160,000 and a rusted strut mont, should just drive it till it drops or will it blow up because it goes down the hiway nice. Plus it is paid for.

the input shaft goes in to a gear and snaps in place on that one,it may be the axle or the inner joint your hearing on it,the gear inside will move a small amount but not much,id check to make sure that the axle hasnt become disodged form the transmisson on it ,good luck.