Google is tricky to use effectively these days. :(
Start with the Parts book. Find the part numbers for the blade and refill. There may be several possibilities. Assume they are all possible. With these you can search for new old stock, not just e-bay, but also within mopar specific venders, forums, etc. If you have the parts books for the years before and after - you can check to get a sense of other years were same or different.
For period pictures, I like to start with the factory sales and promotional literature. There's a pretty good collection at Hamtramck Historical website.
The 1970 Hamtramck Registry Library Page (1970 - 1974) Then look for advertizing and magazine reviews of the model. (some adverts are in the Archives section of Hamtramck Historical website).
Finally, hunt for photos of low milage and 'survivor' cars.
While these photos will rarely be focused on the wiper blades, theres a pretty good chance they will be visible in some of the photos.
For searches within FABO, the forum's search function is generally better than g**gle. Admittedly there's not alot of interest on FABO of this sort of original detail.
Here's the thread where I posted the originals on my '67 and there's a link
to originals on a '70 Dart.
Mine have the 'anti-lift' or 'aero' deflector on them, but a different style than on your '73 Dart.
Who knows Wipers and refills? Especially originals
Pictures of '68 with aero type in this thread.
Refills for Metal Wipers
THANKS FOR ALL THE INFO....I removed the ones from a 72 duster earlier this year when i replaced the blades and they were like these but cant remember exactly what they looked like as i just trashed them after i got new blades like an ignorant dumbass
For reference, here's p/n for two years of A-body Anco blades and refills.
1967: 2770123, refill 2771967
1968: 2889962, refill 2771967