What aftermarket parts are available for a 66 Dart? Maybe it's my Google phone steering me towards my 67 Dart, but I haven't seen much support for the early A body cars. I haven't done any deep dives though.
When you guys think "aftermarket parts", you are thinking about repop parts. The project cars on that channel are racers, hot street cars etc.
Just for an example, I can walk down the aisles of Carlisle (for example) and come up with a couple dozen sets of used headers that would fit that Dart. Try that with a C body... Want to find body parts? Again, tons of used parts and some repop stuff out there. Layson's has a lot of repop trim if you want that too.
It's apples and oranges.... If I were to give advice to someone who is set on building a "project car", but has never done one, I'd probably suggest a '68 Camaro. You can literally buy everything for them.... and used stuff can be had without looking under every rock.
Now, IF YOU ENJOY LOOKING FOR PARTS, then do whatever car you want to do. There's tons of rare cars out there... Hell, I'd love to do an Avanti, but it's not in the cards. There's more challenges and whatever...
But a basic, real, honest to ****, project car is tough. If you want to restore, you have to go one direction. If you want a hot rod, you go another. Uncle Tony's channel is for hot rods built in the back yard. It's not for the guys that worry about having a date coded grease cap on their wheel bearings.
Look around your garage.. If there's tools, tool boxes, and parts, then you probably "get it". If there's tile on the floor with posters and collectables, well, you probably don't.