I've been using moly grease on all the driveshaft fittings... The diagram below shows specificly where the moly is called for.. on sliding joints such as the double cardan and the slide yokes..

<img src="http://personalpages.bellsouth.net/d/a/dandeman/photos/driveshaft.jpg" alt=" - " />

I use Mobil moly grease <img src="http://personalpages.bellsouth.net/d/a/dandeman/photos/molygrease.jpg" alt=" - " />