Steering Coupler ?
Its just a rubber seal that keeps the grease in and crap out of the coupler. I don't think I've ever seen them for sale by themselves. Usually part of a coupler rebuild kit which includes all the pieces inside the coupler: cross shaft pin, two "shoes", spring clip that holds the "shoes" in position, roll pin, grease seal and retaining cap. I just got done rebuilding mine. Only hard part is bending the tabs on the retainer plate over the seal and coupler body. A vice to hold the coupler, a small punch and care will "get er done". Prices: $13 to $17 for a kit. I got mine from a vendor at Mopars at the Strip this year but you can find them on Ebag, swap meets, maybe your local dealership and probably autoparts stores. Do an online search for Mopar steering coupler and you'll get a bunch show up.