I mounted our older TV a few weeks ago. The hardware I used were metric, 8MM with a coarse thread. The mount I bought also came with a set of M10 and M12 hardware. For each bolt diameter, there were two sets of lengths that came with it; I would estmate the short length was from 20-30 MM and the longer one was about 40-50 MM. If possible, I'd check the depth of the mounting hole with either a pin or paperclip and bring that to Rona or Homedepot to check the length you'd need.
Hope this helps
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