Thank you to everyone that contributed to the thread. It helped me immensely as it almost appeared I knew what I was talking about with the mechanic. I tend to get the run around being of small stature and not a man. Here's what the mechanics (that I changed) said in their job sheet.

Found the rear driveshafts front universal joint to have excessive play causing vibration. THis the the furthest forward universal joint on the double cardinal joint as there are 3 universal joints. As a stating point to replace that one universal joint and then to road test. Supplied and fitted a new front universal joint for the rear driveshaft. Greased. Tested driving on motorway and vibration gone. Hallelujah. (i SAID THAT, NOT THE MECHANIC)

2.25hrs labour in total. And a $58NZD part. What a difference it makes on our tiny roads having something i can now control!

Thanks again everyone for your inputs.