Ford Motor Co. is saddling up to celebrate the 50th anniversary of that original “pony car,” the Mustang. And it’s going to get plenty of help, with 50 different companies planning to join in for the celebration by producing a wide range of products meant to commemorate the special occasion, everything from Mustang-emblazoned jackets to watches to video games. They’ll use a new black-and-white logo featuring the familiar galloping horse over the words, “50 Years.”