I remember seeing them all the time on the road back in the 90s and early 2000s...Chrysler 5th Avenues, Dodge Dipolmats and Plymouth Gran Fury's.
One local gentleman had an early 80s Dodge Diplomat 2dr in excellent condition (nearly show car quality, always garaged, never drove in the winter, gold and had that 2dr side profile with the bulge over the rear wheels...nice car).
I haven't seen that one around since early 2000s, but it was his summer daily driver.
A few years ago a NW Iowa man had passed and his large collection was Auctioned off near me. Had a ton of Mopars and Oliver tractors. Went to the auction, not a lot of 60s/70s stuff, but a couple of old 70s trucks and MANY M Bodies (Plymouth Gran Furys, mostly, as well as a few Chrysler and Dodge models). That's the last time I saw a whole bunch of them at once. Don't see them much anymore.
Of course, I see 05-up Chrysler 300s, Dodge Chargers, Dodge Challengers everywhere now (more Modern Mopars).

JS