Just adding to the chorus here, but...don't run very long without that bracket for all the reasons others have said. If that bracket is loose or missing then all the strain is left to the two main starter bolts to deal with and God help you if one of them is loose because one will snap off flush with the block and leave you with a very unpleasant weekend chore. Replace both bolts if that happens too - not just the one - as the other will be stressed to the breaking point without you even realizing.
(Usually the broken end comes out fairly easily providing the previous mech didn't use loctite on the thing. What I usually do is take an old starter bolt, grind the end into sort of a chisel shape, reinsert it in the hole, then try apply pressure and wind it out slowly. It will *usually* pick up the break-line on the bolt remnant trapped in the block and slowly wind it out. Usually. Failing that, something from Snap-On called a reverse-twist drillbit works well too...though drilling through Grade 8 bolt remnants without slipping into the surrounding casting is not a task for the faint-hearted.)
