You may have to use a bolt with a non-threaded shoulder longer then you need, then cut threads down to where you want them. Once that's done, cut the extra length of threads off. Pretty much make the bolt that you can't find. A new sharp die with good cutting oil will make short work out of most bolts. Grade-8 bolts cut a little hard, but most any grade-5 will thread pretty easy. I would use a grade-5 bolt.
Drill the hole slightly smaller then the shoulder of the bolt, then when you draw the nut up tight, it will align the parts and fill the hole completely. You may have to use a metric size the stay undersize of the standard bolt, or even the other way around using a metric bolt. You can always get a reamer in almost any size you want, check with McMaster Carr, they have everything.
Joe
