SoCal Hiker, the "old" trail referred to here joins the Main Whitney Trail at about 20 paces "downhill" of the John Muir Wilderness sign. Going up, you'll hit the main trail and turn left to continue ascending. Coming down, once you see the JM Wilderness sign continue about 20 paces and you'll see the trail on your right. If you come to the rock-hop crossing of the North Fork, you've gone too far and need to retreat a few dozen yards.
There are no signs or markers at any point for this trail, but once you've seen it joining the main trail on your way up you'll have no trouble identifying it on the descent.
