Well the replacement driveshafts arrived this afternoon while I was away on the second part of fixing an old clients computer, which ended up being a faulty telephone extension cable and nowt wrong with the system at all !!! explains why I found no fault with it when I had it here !! another 2 hours wasted !!
Many thanks to omegod for the prompt and efficient supply of the parts. Both now fitted and torqued up .. although 50nM then 60° then 15° didn't feel that tight..... they will be checked every oil change now (5000 miles). Ran out of daylight at the end so all its had is a quick trip around the block, no nasty noises, vibrations or abnormal feel at all. Does feel very low at the back end, but perhaps that's because I've spent 6 weeks driving the Disco in a "sit up and beg" seat position, I'll check out the rear shockers tomorrow.
Once again, many thanks to everyone for all the positive inputs and advice, and a huge thanks (and apology) to Daz and tigers_gonads regarding the gearbox. That is being transported down to me in 10 days time and will be wrapped in clingfilm and stored in the shed as a spare, just in case. It now owes me far more than anyone would pay for a 2nd hand gearbox, so I might as well hang on to it.