Pulsating Low Pitch Hum/Drone

Does it change (or go away) when cornering?

Thank you, we are locating high quality gear oil, what is available (I'm told) isn't good quality. I will notify you on the results.

The rear engine mount at the back of the gear box. I will look in to this... would this be (if broken or worn) be causing a sound such as described?

No. The sound is very steady, wether upon cornering or taking the car out of gear and coasting, the sounds remains. The "pulsation" decreases with the decrease in velocity.

It's hard to describe; pulsating is the best I can come up with. It would be similar to the sound of a truck tire in balanced perhaps.

The tires on this little car have been replaced, balanced and the alignment numerous times which lends to another possible clue. Regardless of multiple alignments, it wants to pull to the right

I replace the rear engine mount every year
Not to expensive and takes 10 minutes to change 
Will reduce vibration if it's worn or failed 
Your problem could be a worn uj joint on the propshaft

After a short drive place a hand on each front wheel if one side feels hot you have a sticking caliper this could cause pulling to one side 

This is fantastic información! Thank you.

Once I am able to do your troubleshooting discovery methods and gather parts (I prefer original Suz parts and have to order from agency) and oils, I will let you know how things go!

Any other things you can offer, I'm all near hearing it and sharing with the mecanico. He too is open to suggestions. Your help is much appreciated!