The Kuryakyn shortened Interstate spark plug runners have been out of production for years.
The std/tourer ones will work on an Interstate just fine. You probably don't have to take the pods off, but may have to loosen them up a little.
They have to be removed to change plugs, so if my plugs were years old, I'd do them before the runners. NGK/NipponDenso plugs are cheap (and all you need).
I get the impression the Std/Tour version will differently than the previous version designed for the I/S. If this is the case, can anyone describe how that might be?