As Warlock III said there are bushings in the distributor housing itself, but the one I am referring to is mounted in the block. There is a Mopar tool to Knurl the bushing to take up the slack created from wear. There is also an intstall/removal tool for that bushing as well. The distributor can be checked once it is removed the bushing in the block is not so easy to check. I've only seen two that needed replaced the rest could be knurled with the tool. This bushing is much like a pilot shaft bushing for a standard transmission, it mearly keeps everything in alignment and restricts movement. If it has enough wear it will let the shaft move around causing wear to your distributor and finally your rotor will rock around and cause irratic misfires and if severe enough could crack your cap. When you remove your cap inspect it throughly to see if the rotor has been contacting the cap, this could indicate a problem with the distributor or the in block bushing. Also when you remove the cap, grab on the distributor shaft try to move it in all directions and see if there is excessive play. Try to turn it back and forth by hand as well, if you have a lot of play then your distributor gear is probably worn as well, this gear doesnt come out with the distributor body when you remove it. All of these things directly affect your timing. Just more food for thought and things you can check once you start your major tune up.