grinding in the drive train

[ahlem]

2001 X5 105,000 miles, automatic transmission. There is a grinding on occasion in the last day or so especially when going in reverse up a slight grade and turning the wheel.
Something is binding and keeping the wheels from turning. If you've ever had to limp a car with a flat tire over to the shoulder at extremely slow speed, that's what this feels like. If I switch between forward and reverse for a few gentle feet, it seems to resolve itself. I'm guessing it may be a CV joint in the LF axle but would welcome any input before I crawl under there later today.