Back together after what? Paint? Patching? You didn't keep the old hardware?
Get a 1/4-20, 5/16-18, 3/8-16, 7/16-14 bolt and start trying them in the various threads, captive nuts or clearance holes and make a list of length and quantity. Not that hard. Some will be screws, 100 deg and 82 deg flat heads and Pan heads.
