If the parts are going to be reattached with bolts, I strongly recommend precision-reaming the holes and using shouldered Allen head bolts to eliminate any slack between the parts. That's particularly true if you're working with stressed parts like crossmembers.
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!