A bunch of interesting stuff posted recently by the San Diego Air & Space Museum (SDASM) Archives on the Flickr Commons.
What appears to be a windtunnel model of a swing-tail CV-880/990 variant modified into a "Guppy" transporter, presumably for Project Apollo hardware.
https://www.flickr.com/photos/sdasmarchives/46806271764/
https://www.flickr.com/photos/sdasmarchives/46806262514/
A purpose-built six-engined tail-sitter transport for the Saturn S-II stage for the Saturn V rocket.
https://www.flickr.com/photos/sdasmarchives/46614588765/
More Convair / General Dynamics (GD) System 476L (C-141) illustrations and mock-up photos.
https://www.flickr.com/photos/sdasmarchives/46614590185/
https://www.flickr.com/photos/sdasmarchives/46614588285/
What appears to be illustrations of the Convair / GD CX-HLS (C-5) proposal.
https://www.flickr.com/photos/sdasmarchives/32587583147/
What might be a Convair / General Dynamics Advanced Medium STOL Transport (AMST) proposal (?), powered by four (4) high-bypass turbofans.
https://www.flickr.com/photos/sdasmarchives/47477227802