The Stovebolt Site Forums The Shop Area Driveline Intermediate shaft AKA jackshaft

So I found the part I need for my GMC 47 1/2T long bed. I was cleaning it up and it looks ok. I would like to change the bushing and the bearing to start from fresh. The bushing is a little worn and the bearing is who knows, but, I don't want a grenade. Does anybody know if these are available? Is the bushing the same OD/ID as the propeller shaft bushing? I was going to replace the cork seal with a NAPA seal in a machined collar as per a thread on oldgmctrucks.com. I wonder if the same treatment could be used with the rear ball collar that resides on the propeller shaft housing? That piece has a compression collar but wouldn't the modern seal work there also? Lastly, what stops the oil in the front part of this unit from mixing with the grease in the rear section. The propeller shaft has the oakie bushing and seal but I do not see a seal between the two sections of the jackshaft. Does the bearing act as a seal?