I'm looking for a source for "timberlock" fasteners. It's a bolt threaded into a steel dowel that's at right angles to the bolt. Thanks

I think "Timberlock" is actually a patented trade name of the Timberlock company. Perhaps they have a web site. I have also been involved in jobs where a local steel fabricator made up similar fasteners for a specifid job. Be sure to have the fasteners designed for adequate strength if you go the shop made route.