single to bench seat conversion

[blackfinger]

Anyone know the proper bolts/washers for fitting a bench seat in place of a single? Took the single out, bench in, holes line up fine, except for the big middle plate with a huge hole in it, whats the best thing to do with this? Old bolts from the single have too small a head for the bench, they pass straight through the mounting on the bench. Should they have big ol' washers or something? Will they be long enough also? Was given new seat, but no bolts with it

[trigger]

Just put a big washer on it