If your not familiar with the MPC the Letter to the left identifies the type of vehicle then there is the cubic inch engine size. As we can see there are only two Mustang applications and since it has the D2 part number and the Motorcraft on the filter for those looking for original filter for their car is could limit the possible number of buyers if they are looking for all the right details for their earlier cars listed in the MPC. For others it would be better than an aftermarket.