I strongly suggest that Loctite will NOT cut it in this application, as there are too many repeated stresses on the nuts and bolts when steering that will ultimately make the nuts back off. That's why they were used with lock washers and pinned originally. Do NOT rely on thread lock in this situation.
I looked around to see if the originals were available - NOT. Not even a part number, as they were included in a coupler package.
That being said, similar bolts as described above will be available at good suppliers, but without the hole, which in my opinion (which may mean little! LOL) you MUST drill and use pins and lock washers.
Yes, drilling accurately through the threads of even a slightly hardened bolt will be challenging, but not impossible. Here's my suggestion:
Go to a good machine shop with the original bolt as a guide, and the new bolts. Get a throwaway nut of the softest steel (non hardened) that fits and spin it on (perhaps double nut it to keep it in place), chuck it in a holding vise and drill through the nut and the bolt using a drill press. Little to no flash, the hole will be properly centered, away you go. 5 minutes at best...