Driveshaft center support bearing

[Dooley Dude]

Changed the oil in my '85 C-30 today. Also wanted to look the driveshaft over, since I've been hearing a sort of whirring sound, most noticeable at low vehicle speeds. Sound does not change when I kick the trans out of drive. It varies only with vehicle speed.

Everything looks okay under there. I shot a little grease in the slip coupling between the front and rear driveshafts. Doesn't seem to be any slop in the U-joints, or in that bearing,but it does look pretty old.

I check parts prices on rockauto, and the parts are pretty cheap. Read the Haynes manual and it seems pretty easy to do. I'm thinking I might do the bearing and both U-joints just for peace of mind. I don't run a lot of miles, but heck I've owned the truck over 10 years.

So what do you guys think? Drive it 'til it breaks, or go ahead and replace it?