They seem relatively simple to make from scratch, I'm guessing 7/16 BSC bolts and stud?
What size/thickness would you say the strap is made from?
How deep is the foot on that bracket where it sits on the strap?
I have a mate who could machine the brackets easily, although now would be nice obviously!
Scott
OK here's a shot from the side. The material for the straps is 7/8" x 5.5-6mm depending where I place my vernier. The lug that holds the footrest is about 2 5/8" long......5/16" fixings. Ron