Some interesting images have been posted on imgur from the 1986 Movie, but I don't think we know who posted them there.
Since the background artwork was taken from a TFW member who posted them up over a year ago, the rest could also just be a collection of images that were obtained from various websites.
Either way, it is a nice collection of images in one place, mirrored at TFW in case the imgur gallery is taken down for using other people's images without permission.
Also scroll through the original source for the background images, as he did quite a few of these composite images from the various Gen1 seasons and Movie, by taking screenshots from the cartoon from moving scenes or moving Bots, and removing the Bots from the foreground (if they were moving). He explains the process in post #83.
The Animation Cels included in the imgur gallery are also fascinating, as some show different layers of various scenes (as they are drawn in layers and then move independently, rather than redrawing the entire shot if only something in the foreground moves).