Probably not, but Silvretta don’t make those 404’s anymore and I don’t think they come up much 2nd hand so I think you might need to look somewhere else. I’ve not seen much that works with mountaineering boots, people seem to release approach skis from time to time but they rarely last on the market for more than a year or two.
I’d like something that worked with mountaineering boots as well,, it would be nice to have something that fits to an old pair of skis just for cost reasons but something like the STC ones appeal as they’re light enough to stick on the sack and still move around which an old pari of 180cm skis just wouldn’t be.
This is a pretty niche market I know some people use the same boot liners in climbing and AT boots and then ski in with the shells to swop over, I can see the sense in that. Some plastic boots will fit in AT bindings, Koflachs certainly did at one point and maybe the Scarpa Vega or Omega does now but I was personally more interested in lighter non-plastic boots but my need is probably even more niche again