so....
Went to shop yesterday morning, got the part for 2pm, wrong part...too long.
Went back and got a refund, they ordered the "correct" part for today 2pm.
Went to fit it, still too fooking long, so went back and got a refund.
Called GSF and they have the correct part and correct part number from the belt that had snapped. I've put it on hold and a friend is taking me there to get hold of it, I'll fit it when I'm back.