It's the pink one, right? I've had it for years, and agree it sounds great, natural. I figured it was mono, actually. But on the inside jacket, after the liner notes, in fine-ish print, it says "Electronically re-recorded to simulate stereo". Mine's a radio station promo copy, KG 33341. And the white promo labels all say "Stereo" Maybe there was an actual mono issue? Or maybe they just lied about it because it was 1975 and they figured that real mono would turn people off. The only place I see any mention of that re-recorded business is that one spot at the end of the liner notes.
No matter, somebody should buy this. It's a really, really good collection of Ellingtonia, and with "The Clothed Woman" & "New York Blues" leading it off, a pretty damn important one. Definitely a transition period for Ellington, the shift from Greer to Bellson, and from Hodges to Smith occurs right in the middle of Side 3, and, yeah, it's sudden, to put it mildly. But even the "curiosities" like "Joog Joog" are quirky in the way that Ellington's lesser works often were. And oh yeah, You also get "Snibor" and "Monologue". And the original "Jam With Sam".