Gary,
you can get an, ms bolts from Coast Fabrication, Wicks Aircraft and many of the homebuilt aircraft suppliers. I am sure there are others. Wicks seemed to be better priced but they do not carry the big bolts needed for some of the old design cars, like mine. One word of caution. For simplicity these bolt diameters are measured in 1/16th of an inch so a 7 is a 7/16. Length is meaasured in 1/8 and if they stuck to their system a 32 would be 3 inches long, they aren't. the bolts are actually a a little longer, I suppose for washers. So when you order make sure the actual length is what you need. Back to the clips, I don't know if I would trust the e clip on a rotating assembly, like your 1/2 shaft. As I said, they were invented for stationary header bolts. If physics apply, when the 1/2 shaft turns the heavy side of the clip will work it's way to the outside and leave the opening of the e clip ready to exit the bolt. I really think you should safety wire that assembly.
Bill
Sorry Gary I missed the Metric part. I would still try Coast. They should know a fastener supplier that will have them.