I looked everywhere and I can't find this size string lock insert block. Most of the inserts are 6-7mm long, but mine is ~8.4mm and the position of the hole is more center biased.
Yea the OFR ones are very short and it fell to the bottom, the closer fit was another licensed jackson trem, those were a little longer but I still had to turn the trem upside down to line up the hole with the string lock screw.