I had a steering issue a while back and changed the PS pump on mine ('01 2500 CTD). I got a rebuild kit off ebay for the vacuum pump and rebuilt it myself. Not hard to do at all and a heck of a lot cheaper than a new vacuum pump. I wasn't having any issues related to the vacuum pump, but they mount together and to ensure there wasn't an oil leak, I removed both. Figured I might as well rebuild the vacuum pump while I had it off.