It's my opinion that the "mystery date" start and stop for the McRib is entirely dependent upon the availablity of the "mystery meat" they use to assemble a McRib patty... for some reason, McDonalds gets the short end of the stick when it comes to mystery meat supply... however, Taco Bell has demonstrated that they have access to a lifetime supply of MEEF.
What I'm trying to say is
"I'M IN!!!"