This is always a interesting subject. On the pictures, starting from the top( All factory original)Yam 90, Tohatsu 90 and the third looks ordinary SS or acid proof... But they are original bolts from a CMC transom jack, rated for 300 HP. The Japanese bolts are unmarked, Tohatsu looks like galvanized.
The CMC bolt is marked F593C. Don't know what that means, but threads look pretty standard.
Makes me wonder, as the forces are pretty bad on a lift(with a 300 hp lupmp hangin on it), do You really need fine threads in this application as coarse is OK for CMC? Believe that finer pitch is better due to getting the correct torque on the bolts, but most transoms have a core that flexes slightly( plywood or other) so that is not an issue on boats(?).
Not that I would recommend taking any risks on such a vital equipment, but still as the originals are made of gold(price wise anyway
) would be nice to fully understand the black magic of transom bolts ...for sure there must be industrial applications with close to same requirements.