I assume you are in the UK since not too many Grifters made it to the US.
First, we need to know the model... MK1, MK2, MK2 S.E., XL, and Super all had certain features that were found only on those models. Nobody can point you to information if you don't provide this.
Next, since the bikes were made in Nottingham and not in Taiwan or China it is a good bet that at least some of the parts were made there too but of course with a spattering of Asian parts. What you need to do is to outline the parts you need, then look closely at each part and see if there is a brand/model name on it. Even the saddle (which I suspect was made by Velo or Viscount) may be common- if you provide more information.
I looked in the Y ! A archives and noticed you asked this question before. Did you go to http://thecheapbikeshop.com and email him with a list to see what he might have?
Finally, be well advised that it will very likely cost more than the bike is worth for outfitting with NOS parts... but it is your money!
