In reading this, I had some thoughts since I've had to deal with metric hardware in a sideline project making cam chain tensioners. If you did some digging might find the 8 is a rounded M8-.075 fine thread pitch. They do two fine pitches, M8-1.00 and M8-.075 threads per millimeter. But I'm guessing. The coarse 8mm thread is M8-1.25 threads per mm. Here is a link to the ISO charts I buy bolts at Fastenal, where they can be ordered individually (if not in stock and usually not). Problem is washers and nuts are not sold in singles. Just pointing out the alternative. I am fortunate in having a really good old style hardware store for the goofy or single stuff. I use Fastenal for my quantity purchases though.