[Arran]

Arran,

judging by everything being this dirty and rusty, the replacement (if it is) is more or less contemporary or in any case quite old and from the era when people still used and repaired these radios which I think could be 40-s to 50-s. For me it is all old and acceptable, unless you are Russ and doing trye to factory restoration for a museum

Mike;
  RCA slug tuned IF cans were 455KC, were used for a number of years, and are quite easy to find. Besides it looks out of place being shorter and of a completely different design, it is a restoration after all, not a repair.
Regards
Arran