Koechlin sym. 2: Op.196 (1943-4) Premiered Aug. 29 1952 by the Orquestra Sinfonica Naçional under Jose Pablo Moncayo.
I Fugue (arr. of Fugue sur un sujet d'Ernest le Grand, op. 126) (7'55" in the recording I had - still on my iPod but unrecoverable far as I know, making this a better idea...)
II Scherzo (l'âme libre et fantasque) (based on themes from the suite for Cor anglais) (11'41" likewise.)
III Suite of six chorales (Requête à l'inconnaissable - Aegri somnia (from op.90a, 1924) - Pour la consolation des pauvres âmes (op.111/7, 1929. Strings and harp) - Les Goëlands sur la Mer - Berceuse marine (op.109/4, 1929) - Vers la cime)
IV Fugue on a Theme of Catherine Urner (from op.114)
V Finale (new to the symphony, not an arrangement.) (III-IV-V totalling 22'13" in the recording I had.)
Discussed in Orledge, "Charles Koechlin (1867-1950): his life and works", e.g. on page 200. ? because a lot of it is no longer under Google's Preview-view and I don't have the book

Also see e.g.
http://classik.forumactif.com/t3654-koechlin-les-symphonies.
Since there are in fact five movements to the symphony, not four, not sure how they correspond to the four on your mp3s, but will check. I had the same issue (actually, I think I had three mp3s, not four, my last being Suite of Chorales - Fugue - Finale, with unknown prov., conductor, etc. ...)