Hi Ace!!
The "wobble" was first noticed as a periodic (regular) bump when doing about 15kph, almost like a pulse. It was partially resolved by changing the tyre on the rear right, it definately had a fault in the tyre wall. But it does still seem to roll a little rough and yes it vibrates (within tolerable limits) around 80-100kph. It's not a big problem but it does seem a bit symptomatic of some rising issues here and there..
The diff noise was only present in the last drive, this was after a bit of 4wd fun. Definitely don't want to shag out the diff if it's avoidable..
As I've not long had the car, I want to go over it bit by bit and do everything. That way I can start a maintenance regime from scratch.. But it's just taking me a little time
I will progress up the drive train and replace drive shaft seals, change to 1ltr transfer case (and eventually 6.5 reduction gears). But in the process I'm hoping to solve the vibration/wobble... And yep the front bearings etc will also be done, I just thought I'd start at the back as that's where I think the problem might be..
How do I check the universal joints?? Am I looking for play it them?
Is the manual this one??
http://www.suzukiinfo.com/sierra/suzuki ... 413fsm.pdfI haven't had a good look through that manual but the Gregory's manual and I are getting well acquainted

I'm afraid I'm not sure what a kingpin is.. I will google it, but that will give me more food for thought on finding out..
Thanks for your input mate!! All very much appreciated!!