I'm still trying to find the source of my driveshaft vibrations. This weekend I took off the rear driveshaft from the center bearing to the differential. I noticed the slip yoke is air locked. There is no slop but it feels like a shock absorber when you push against it. The grease causes it to seal and the air can't get around it. I cleaned it out as best I could but I think it should have some sort of weep hole to allow the excess grease and air to come out. I couldn't find one and checked the front driveshaft and didn't see one on there either. Is there supposed to be a hole and mine is just rusted shut?

By the way I don't think it's the cause of my vibrations but that's another post. It's been driving me nuts and it's getting worse. I'm almost to the point of letting whatever it is break so I can find it.

Thanks!