Perhaps I wasn't clear. The 12v fuses belong in the 12v fuse box and are still available from Victory. I didn't suggest for them to be put in the 125v fusebox. As others has said, although the fuse blows at or just above 15A the energy to be disappated is much greater so the materials are different.
There appears no source of the 125v 15A fuses, though Littelfuse must have sold them to somebody for use in servers, audio equipment or similar. So someone should have some left over. Are the Optifuse. type ANM125-M available to buy. Close match and 125v