Radio Controlled Sandcrawler Engineering Pilot: An engineering pilot is a package sample of a product, put together by Kenner in order to ensure that all the toy parts, inserts and paperwork fit properly into the box. Typically, EPs are made with plain white boxes, which are of the same dimensions as those used for the final production products. This is the case with Sandcrawler you see pictured above. Sometimes, EPs even have early versions of stickers or instruction manuals. I've seen some with instructions that were literally photocopied from hand-written mock-ups.

In the photo you see the toy itself, the inserts and the white box. That written-on piece of paper you see taped to the lower cardboard insert names the toy and lists a price ($4). My guess is that, after it had served its purpose, it was sold through Kenner's employee store.

This kind of prototype may not be as exciting as some others (this Sandcrawler, for instance, is identical to the production model in all but its box), but they're quite interesting nonetheless.