Most nuts are metric, but this is a drum brake, so I am thinking they may have stayed with standard. 3/8" comes to 9.525mm. ((3/8)*25.4mm=9.525mm). 10mm wouldn’t fit.
Most nuts are metric, but this is a drum brake, so I am thinking they may have stayed with standard. 3/8" comes to 9.525mm. ((3/8)*25.4mm=9.525mm). 10mm wouldn’t fit.