E=1980s, 0 year of decade, A=ford alphanumeric value for Ford full size vehicle, E=part.
Decoded=1980 engine part/block. One thing of note is that the number is unique to the original year of introduction. If the part didn't or hasn't changed it will retain the original number. There is a second set of numbers that tell the exact day, month and year the part was made/cast. The typical casting date looks like "6M08". You will usually find these on a riveted tag, stamped, or cast in the part. Your D3 number is a bit out of order from what I'm used to seeing so that may not be the casting date. Below is how the dates are decoded:
Breaking down a casting date: 6M08
6 = The year of the decade. "6" for 1986, 76, 66 or what ever
M = The letter of the month. (December) (A=Jan B=Feb etc)
08 = The day of the month. (8th)
Hope that helps