Bolt for rear frame cover?

[FlashyJMG]

Hey there, I bought my gz250 just over a month ago, and am trying to replace some of the oddities the former owner(s) subbed in.

I ordered a new bolt for the rear brace, and it isn't long enough to go through the rear fender, the frame, the spacer, and the chrome frame cover. The part # in the manual is 01550-08553, but the one they ordered me is 01550-0855A. I googled it and found that this bolt has superceded the original?

Can anyone help with this? Do I need the spacers? How do I put the backrest on with the new bolts? Can I just buy generic bolts, and if so what size should they be?

Thanks.