Over the last several months I've been noticing a slight humming noise that starts around 40mph on up. I know it's not the tires because I replaced the worn out BFG's on it with new conti-extremes last summer, I put those wheels and tires on my wifes car a few weeks ago and installed a new set of Kumho's. The noise is still there.

My first guess is the driveshaft support bearing. Does anyone have any experience replacing these on the 124's and does it usually cause some driveline noise when it's worn out? I just had the front flex disc replaced last year so I know that's good but the support bearing is original so it's got 174k miles on it. Should I start there and just replace it because they're relatively cheap and it's got a ton of miles on it?