OK, now I realize they went with the 7/16" bolts because M10 x 1.25 bolts are kinda pricy in the length needed for the 2" BL. ($10-12 vs $1-3 for the 7/16"). For those 6 bolts really you could use any size or thread type you want since they use their own nuts.

I'm still trying to find the important bolts which is no surprise since others went thru the same thing.

If anyone else has an in on the bolts, just to remind, you need:
(2) M12 x 1.25 pitch x 180mm
(2) M10 x 1.25 pitch x 160mm

EDIT TO ADD 11/14/06: I found the M10 x 1.25 pitch x 160mm here locally. $12.40 each!