Unless you're interested in doing a 100% correct restoration, just eliminate that piece and substitute lock washers, or use a drop of blue LocTite to retain the bolts. If you opt for the LocTite, clean the bolts and the female threads thoroughly with spray brake cleaner or some other type of volatile solvent to be sure there's no oil on the threads. I'd use threadlocker if it was my project.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!