Midnight Express

Seeing the diecasts for sale in another thread brought a question I've had for a long time.

Was the Midnight Express truck a f'real Chrysler offering, or just a 'tribute' kinda thing someone did? I've never been able to see one in person or find much info on the web, but I've seen several different pictures. Some say they're legit, some say they had 440's, some say they were legit with only 318's, etc, but I never see them in the Mopar books, even though they almost always include 'Lil reds.

What sayeth the hive? Pics of factory sales literature is, to me, the end-all proof of existence of this non-Ford Bigfoot.