Wouldn't it be possible to take one 2" long 10mm bolt, grind down the diameter on half of it, approximately 1mm, and re-thread it with a 8mm die?

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Tomas, Sweden
1966 Mercedes Benz 230S with OM617.912, automatic. Disk brakes from W108
1983 Mercedes Benz 300TD grey, OM617.912 and 5-speed manual
1983 Mercedes Benz 300TD blue 7-seater, OM617.912 and 5-speed manual