Bolt mystery

[MikkiJayne]

Is that M10 or M12? How long?

You definitely don't need to remove the gearbox to change the rack, and especially not on a manual. The bolt which goes in that location on a manual has a flat non-tooled head (hard to describe, and I'm failing) and has a nut on the engine end. Its not the one in the picture.

There are two places with bolts of that format btw, but which it is depends on the diameter