Hi Stig,
Thanks for the update regarding 42-78165.
Had another look in the Schiffer book and found the following, also under the 724 BS section.
Quote -
42-51590
estiny's Tot: Arrived August 27,1944, to replace 42-78165.
Crashes near Bologna,Italy, April 24th 1945. Original Pilot Gerald Apple. Battle number 24.
So 42-51590 replaced 42-78165 from 27th August 1944 and crashed April 24th,1945.
And as I have already put in my earlier post, 42-78165 Arrived July 1944, was damaged by fire and was Salvaged August 23rd 1944 which fits the narrative od being replaced by 42-51590 from the 27th August 1944.
Joe B's page has 42-78165 Salvaged 24th May, 44 same as you give for the 451st's webpage.
Alex