Interesting, rare and sometimes cheap ebay items.

[heroic_decepticon]

Optimus Prime G1 Prototype (to create Hasbro instructions for G1 Prime) ??

http://cgi.ebay.com.au/Transformers-Optimus-Prime-G1-PROTOTYPE-Very-RARE

looks pretty good, but i have some doubts. I suspect there could be a fair few OPs released with those variations, rather than there being ONE prototype. Besides, i think it's unlikely that top companies actually boxed up prototypes but that's just me.