I have a vibration (rumble) in the front driveline (of my 1995 Grand Cherokee) that I can't track down. I had a new front driveshaft made (with all new CV parts and yokes) because the old CV joint took a dump. Before it did, it shook the driveline pretty good. I put the new shaft in, but still have a vibration, especially when I first get on the freeway. If I put the select-trac in full time loading the front driveline, the vibration goes away for the most part. I just pulled the shaft again to check the front diff yoke and transfer case yokes for tightness, and they are. There is a small amount of side play in the t-case bearing, and it is losing oil somewhere (hard to tell).
Could the t-case output shaft bearing be shot or the case itself, or anything else to look for?
With the driveline out it's as smooth as glass.