Originally Posted by
PhilFo
Those look a lot like Modolo holders. When you get the calipers, measure the width of the slot and if you're at 6mm then you can fit virtually anything, even a modern threaded post pad with hemispherical washers for better toe-in.
I'd be wary of using a fixing-bolt smaller than the slot in which it is to go.
You don't want that to move.
I had a similar issue recently (cannot remember which combination of pad and caliper) and made a set of T-shaped flanged inserts, can do that again, pm me if you want to go that route.