For decoding your casting numbers:
The first character is for the decade the part was produced.
A - 1940's
B - 1950's
C - 1960's
D - 1970's
E - 1980's
F - 1990's
G - 2000's
The second character is for the last numeral of the year the part was produced.
(With the first 2 characters you can decode the year of the part. A7xx - 1947, B5xx - 1955, C6xx - 1966, etc.)
The third character:
This character is for the product line that the the part was used on.
A - full size Ford (Galaxie, LTD, Custom, etc.)
B - Fairlane and Torino to 76, then 77-79 LTD II, then Festiva, then Aspire
C - Mercury Capri (60's - 70's), Escort
D - Falcon, Maverick, Granada, Taurus, 96 and later Taurus/Sable common parts
E - Escort
F - common Tempo/Escort parts (same parts, different body panels)
G - Mercury Montego, Monarch
H - Ford heavy truck
I - (Omitted because it could be misconstrued as a 1)
J - marine (boat engines, stationary power plants)
K - Tracer
L - Lincoln Mark series and regular 4-door Lincoln
M - full size Mercury for unique parts (otherwise, use A)
N - Ford tractor
O - 62 and up Fairlane and Torino, Mercury Montego, Sable, and Lincoln Continental
P - Bobcat and Pinto
Q - (Omitted because it could be misconstrued as an O)
R - Merkur, then Contour/Mystyque
S - T-bird
T - light truck (F-100, F-150, etc.), Bronco, Explorer
U - Econoline van
V - Lincoln Town car
W - Cougar
X - Villager
Y - Lincoln or Mercury/Lincoln non-vehicle-specific part
Z - Mustang or Ford non-vehicle-specific part
2 - Probe
3 - Tempo
4 - 96+ Sable body parts
6 - Topaz
7 - Ranger
8 - Windstar
9 - Aerostar
The fourth character is an engineering number. (Z - denotes an actual saleable part available off of the dealer's shelf)
Much of this information came from an SHO Taurus site but is no longer available on that site.
But don't quote me on those, i just ripped them from some website. For the crank, if you look closely somewhere near the front I think, it may be stamped with the number (Not a cast in munber). I think I've seen one stamped on the first counterweight.