72 Duster with a Rusty fuel system....how do I avoid this???

Google searches are pretty cool. Remember when you had to wait until the store was open to find stuff out?
Looks like the filler neck seal fits from 1967 to 74.
Mopar Parts | MF296 | 1964-74 Mopar Filler Neck Grommet; 1967-74 A-Body, 1964-69/72-74 B-Body, 1966-68/70 B-Body Wagon | Classic Industries
I recall reading somewhere that the 68-69 Tanks fit but hold the full 18 gallons. I'll probably go this route.
I expected this stuff to cost more. This is too cheap to put a band aid on it!