Classic & Vintage - Raleigh DL-1 Tourist - Need help finding a part

I've sorta exhausted my usual sources, so I hope someone on the forum might have a part I need. I've almost finished the restoration of my DL-1, but I'm missing a bolt. It's the bolt that holds the seat stay and the chain stay together (near the rear wheel) and screws into a nutsert. The chain guard is also held in place by this bolt. It is approximately 1/4 inch in size, but is an English threaded bolt. Neither SAE nor metric will work. I'm guessing it is Whitworth. I think the DL-1 might be the only Raleigh that uses this setup, as none of my donor bikes (Raleigh Sports) have the bolted-together rear frame. If anyone has one of these, I'd be very grateful and would gladly compensate your efforts. My email is luckychow99 at gmail dot com.

Thanks!
Darryl

I was able to obtain a correctly threaded bolt from Yellow Jersey of Madison, WI.

I was able to find this bolt at a Trimuph motorcycle dealer. Well, actually, he ordered it for me. It is a 3/16 bolt, with 26 tpi and is 3/8" long. I bought five, if anyone needs one.

Reading this, it occurs to me that a DL-1 would be a pretty prime candidate for a belt-drive conversion. I might have to look into that.

But who would possibly want to mess up a classic bike like a DL-1 with a belt-drive? Of course, with the enclosed chaincase, who's to know? :)

Well, I would. But I've also done some pretty rank things to bikes before, like bullhorns on a 3-speed coaster-brake Super Course. There are no sacred cows in my world