This information was posted by 6Stang7 about a month ago in response to a similar question I had.
Use this handy chart to decode all of the Ford part numbers. For example a 1968 200 6 head part number: C8DZ-6049-C
The first two digits indicate the decade and the year;
A = 40's
B = 50's
C = 60's
D = 70's
E = 80's
F = 90's
G = 00's
So the first two digits indicate that it is a "C" 60's and a "8" so that tells us it is a 68 head.
The third digit designates the vehicle model line;
A = Ford full size (Galaxie)
B = Bronco (70-75)
C = Torino/Elite
D = Falcon
E = Escort
F = Pinto, Maverick, Late model Falcon
G = Early Comet (61-68), Montego, Cyclone (69-76)
H = Medium & heavy duty truck
J = Industrial
K = Edsel
L = Lincoln (58-60)
M = Mercury
O = Fairlane (62-68), Torino (69-76)
R = Capri
S = Thunderbird
T = F series or Bronco
U = Econoline van
V = Lincoln
W = Cougar
Z = Mustang
So the third digit indicates that it "D" was off a Falcon.
The fourth digit designates the engineering group;
A = Chassis
B = Body
E = Engine
Or if it's a service replacement part;
M = Ford Motorsport or FFRP
X = Original Ford racing program/Muscle Parts
Y = Lincoln-Mercury
Z = Ford
So the fourth digit indicates that it was a "Z" Ford replacement part.
The next 4 numbers (6049) indicates the Ford "group number" for a head
The last digit "C" on the end of the part number indicates that this part was in its third revision. If revised again it would turn into a "D" and so on. When they reach the end of the alphabet they started over with AA, BB and so on as shown in this "example" part number: D7BE-6090-AB.
Our example part number C8DZ-6049-C decodes as;
C8 = 68
D = Falcon
Z = Ford replacement part
6049 = Head group part number
C = 3rd revision