I have read a few posts that the "clunking" can possibly be temporarily fixed by greasing the driveshaft slip yoke. Could you please give me some guidance on how you actually do this? Thanks so much in advance!!

I went to the local auto parts store, and bought a tube of mobil 1 chassis lube. (the red stuff)
Take the driveshaft out, 4 bolts. Watch that the universal joint caps dont fall off, have masking tape available for wraping them.
When you pull the drive shaft out polish the yoke with steel wool or scotchbrite. Put the lube in the splines, pack it in to the grooves good.
Coat the seal and outside of the yoke. Reassemble you should be good to go. This fix has worked on 4 different chevs I owned. the downer is you will need to redo it every year :(