[Joe Rossi]

Joe;
  Mondial is right, that IF rejection coil is what other manufacturers called a "wave trap", basically a band reject filter that blocks RF interference. You don't need it anymore, I don't think that many sets used them past the early 40s. There doesn't seem to be anything on longwave anyhow other then some beacons, and I don't think any of those are at 400-500 KC.
Regards
Arran

Thanks Arran!