I'm piecing a 90 together from parts and I don't have any "go by's", anyone know the dimensions of the bolts that secure the wings to the bulkhead? I want to go stainless with these. Any help is appreciated.
Those are special body panel bolts with course threads, and they thread into captive nuts. They are a pretty large diameter, perhaps 10 or 12mm. Try browsing the various offerings at mcmaster.com, or order a Totally Stainless catalog.