Some of the L.M.S 4-6-2 CORONATION class locomotives were initially built in streamlined form. Later they were built in un-streamlined form. For a while it was able to discern between the two different builds, by the sloping smoke box of the former streamlined engines. However, these were also later removed, and after that, except for one distinguishing feature, it was difficult to tell which, of the loco's were formerly streamlined..
The distinguishing, and remaining feature of the former streamlined locomotives was the front frame buffer beam.
The former streamlined loco's had a split buffer beam, and those built without streamlining, had an unbroken curved buffer beam.
Former streamlined version as is seen on 6229 "Duchess of Hamilton"
Un-streamed build is as seen on 6230 "Duchess of Buccleuch"