I have recently got this model. My question is, is it really a pre-production or some kind of trial/testing model? The body casting has some weird colouring on it. Please inspect the photos. The friend who gave me this model has some more like these, but he doesn't say much about them, so I can only guess

I will appreciate any help!
I have listed it on eBay aswell - http://www.ebay.co.uk/itm/251988235038
Thanks.