What is a good source for dare coded parts
There is not one greatest source. Most yards and the like HATE people calling about dated this and that. They know that 95% of the time the date they find on their parts won't be the one that the caller is looking for. Been told this maybe a hundred times. Instead your likely going to have to posts allot of wanted ads and hope that someone will take the time to look for you and then expect that you will pay a bonus over the going rate since there is a cost for the effort.
Other choice it to go to allot of swap meets and look through a ton of parts (guys often don't like lugging around sheet metal. To big, to easy to damage ..........
Last and often best choice if your doing a car - especially one that is missing pieces, your attempting to build a top end car or one that has had replacement of parts over the years is to consider finding a parts/donor car, even if its not the same body style. These in the long run can be bargins IMHO. Often builders will take and use what they need and the car will get passed to maybe two to three additional builders before its used up or parted out completely and the parts traded or sold.
Owners of cars from other period have always used parts cars but for some reasons Mustang builders have used them allot less. Possibly since the parts for the plentiful Mustangs were so easy to come up with through the years when compared to other cars. Now with less yards and parts its a great option especially if you can find one built at the same time and plant.