I put in the cush drive rubber for a Thunderbird after herbz had his done and said it was recommended by his dealer. It costs about $80, and the part number is T2012211. I installed it myself, and it's a more snug fit than the stock cush driver rubber. I've had about 7 nails in my tires over the last 2 1/2 years, so I'm familiar with what a snug stock cush drive rubber is like.
