For reasons I won't bother to go into, I need a couple of clamp-on cable stops to fit a standard steel top tube--25.4", if I'm not mistaken. I need the slotted type that don't require that the cable be threaded through.

Origin8 makes them in a couple of sizes, both single and double (I need a couple of singles). Unfortunately, the smallest size seems to be a 28.6. I could make that work with shims, but that seems kind of kludgy to me. (Of course, any clamp-on stop is sort of kludgy, so maybe I'm making a big deal about nothing.)

I've tried and failed to find a source. Does anyone here know where to find such an item?

I used a pair of Sturmey Archer shifter cable stops. I put a bit of fine sand mixed with Elmer's glue on the inside of the bands to keep them from slipping from the greater pressure from brakes relative to the shifter they were designed for. Works well.

I could use same. I have doubles around, but apparently no singles. I've been thinking it but haven't verbalized it.