Sixtrain is a retool of the Return of Convoy combiner Sixliner, made up of six train Micromasters that combine via attaching to robot-mode kibble. When separated, this kibble becomes three different weapons; the legs can mount on San D-Go or Atlan's vehicle modes as a large roof-mounted cannon/thruster, the torso can connect to either footplate to form a twin blaster car pulled by any member of the team, and the gun, fists, and head all combine with the other footplate to form a weapons trailer. Sixtrain has limited compatibility with the "jet-kibble" style of Micromaster Combiner, really only able to swap out his arm or "back" components with others.
Released in 1992 as part of Takara's Operation Combination Generation 1 sub-line, these figures were only available in Japan, and never released in the United States. They were later reissued in Japan in 2003 with slight color changes, and also had their stickers replaced with paint applications. You can see a comparison between the originals and reissues on Brr-icy's blog located HERE.
The figures come complete with all parts to form Sixtrain, but the two white figures do have a bit of yellowing on one side (see pics), however the other side is completely white (if that's of any consolation). It shouldn't be too hard to find replacements for those two though. The accessories are all included, as well as instructions, and un-used sticker sheet. The box is in good condition with only a slight divit in one corner (see pics).
This set will display extremely well either boxed or loose, and would make a great addition to any G1 collection.