trailer hitch bolt sizes

does anyone know off hand the sizes of the bolts that go up through the frame into the nut-sert strip? Also anyone have any tips for removing the bolts on the pass. side next to the gas tank? thanks steve.

M12 x 1.75 x 30 mm

Are all of them the same size? THe response seems to say that, but I was trying to tell what size they were but the two of them seem to be smaller. Maybe it was rust buildup making the nuts look smaller inside?

Oh and
Once again, Proof that searching first works!!!!

If you're using the nutstrips, they are all the same size. If you're using single backing plates and seperate nuts, your guess is as good as mine.