The covers of the original Super Detective Library stories were often less than inspiring or looked — by 1966 — rather old-fashioned, so a number of Jet-Ace Logan covers from Thriller Picture Library were repurposed. That the covers had nothing to do with the stories and didn't even feature the same character didn't seem to matter. At least on Buster Adventure Library 33 the editors remembered to remove Jet-Ace's R.A.F. badge and the Space Command logo from the spaceship...
Cover images of all of the original issues can be found in The Thriller Libraries index, published by Book Palace Books.
Alessandro Biffignandi, reprints TPL 426
Arnold Beauvais, reprints SDL 37
James McConnell, reprints SDL 129
Alessandro Biffignandi, reprints TPL 383
Alessandro Biffignandi, reprints TPL 422