After chasing the vibration and clunk/thud I believe I have found its cause. Either a bad u joint or in the front transfer case. I have people say U joint and other say it is the either the output transfer bearing or the pinion gears inside. I am just trying to get a heads up on what this might be. There is a difference between replacing a driveshaft, a output bearing, or a transfer assembly.

[youtube]https://youtu.be/XOxurGnNkqk[/youtube]

Zerk fittings are found on many 'shaft U-joints , luckily. Get the vehicle up a little higher - look / feel for them,with grease gun in hand " bloat " them up proper with chassis grease . Or at least if you found some goto the Goofy- Lube , they ought to get this right , ya know ?
Any looseness in the "cups" w/needle bearings will feel , and sound much better , leading to finding or eliminating that as the culprit .

Grease will not hurt if fittings are there but absolutely will not stop clunking if it's due to wear making parts loose.

Take one end of driveshaft loose and work it radially, you will find any looseness there in seconds.