Having a cast Aluminium enclosure with the 3mm wall thickness. now I need to mount this to a mounting plate which fixed in vertical walls. can I have some idea on how should I choose the appropriate fastener?

  1. Cast Aluminium enclosure
  2. mounting plate for now, I have placed a 5M countersink bolt


Enclosure can't be changed. this mainly mounts on the railroads it should withstand 20g RMS shock. this is the only way I found to mount the enclosure to the plate since I have to maintain the water-resistance. and have to mount vertically.

Total enclosure weight around 800g

my worry is thread engagement how can select way to mount.

Thanks in advance.