Ok over the years I have lost a few bolts from my car and wanted to know the best place to find sizes. I really will have a hard time just testing out bolts trial and error to find the right size etc. Not sure if this is in the right section, but figured I would start here.

I am missing the bolt that holds the exhaust to the bracket, by the first cat converter. I believe that the bracket that it goes into is self threaded, but that did not work out too well.

(97LT1 and up for these bolts)
I am also missing the bolts that attach the radio to the dash, along with several interior bolts.(speedo housing and panel by obd2 port) anybody know anything?