Steeing Coupler Seal

I'm in the process of replacing the power steering gear on my'65 Barracuda. I noticed the seal for the steering coupler is rotted. There is what looks like a seal cup that fits over the end of the steering column tube. It appears to be part of the coupler seal. I have found several places that have the coupler seal in stock but without the seal cup. What's the story of these parts?