Casting Numbers/ Part Numbers

There always seems to be a little confusion concerning what these numbers mean, and, what the difference is between them. They are, after all, very similar. We'll start with the casting numbers. This is the number which is actually on the part itself. Some have it cast into the part, others have it stamped into the metal of the part, others, like wiring harnesses, have it ink or paint stamped on the part, and some don't have it physically present on the part at all.



Here's how that works. The first digit will be a letter which signifies which decade the part is from. 'A' is the forties, 'B' is the fifties, 'C' is the sixties, etc... The second digit will be a number, which indicates which year of the decade the part is from. So, if the first two digits are C1, this is 1961, D4 is 1974, B9 is 1959, and so on.



The third digit will be a letter, unless it's a part originally intended for something that didn't go into production until after 1970. Then, it could also be a single-digit number, but, not for a Mustang. This tells you which car line the part was originally designed for. This is just what it was originally intended for. They did not use car-line specific part numbers for the same part that was used in several different vehicles. A 66 model 289 hipo engine block will have the casting number of C5AE-6015-E on the side of it. This does not mean that the motor came out of a 65 Galaxie and was put in the Mustang by someone. On the small block V8s, the official "Original Intention" was for the Fairlanes on the 221/260s. That's why the early blocks have an O for the third digit, even though they were also using that motor in other cars, as well. That's why you see some blocks with an A for the third digit, like the 65/66 6-bolt K code motor. That particular variation was designed to be put in the full sized cars, but, was also used in Fairlanes, Mustangs and Falcons. The short version of this explaination is that the third digit tells you what the original drawings had written on the bottom of the page, but, the same part might be, and frequently was, used in several different car lines.But, what those digits actually mean is,

A---Full-sized Ford built after 1957

B---Bronco 70-73, Maverick 75-77, and Fairmont 78-83

D--- Falcon 60-69, Maverick 70-74, Granada 75-82, and, LTD 83-->

G---Comet 61-67 and Montego 68-76

H---Heavy truck 62-82

L---Lincoln 58-60, Lincoln Mark something 61-->

M---Mercury

O---Fairlane 62-68, Torino 69-76, LTD II 77-79

P---Autolite or Motorcraft 62-->

R--- Rotunda 62-69, Ford of Europe imports 70-->

S--- T-Bird

T--- Various trucks and Broncos

U--Econoline van

V---Lincoln Continental

W--- Cougar 66-72, Bobcat 75-80

Y--- Canadian Mercury Meteor 62-73

Z--- Mustang, Mustang II



The fourth digit is telling you what sort of part it is in a very general way.

A-- light truck part

B--Body or electrical component

C--Chassis

E-- Engine/powertrain

F--Electrical/ fuel system

P--Transmission/ axle

R-- Transmission/axle

S-- Truck Engineering

W-- Transmission/axle

X-- Muscle parts

Y Lincoln/ Mercury replacement parts

Z--Ford replacement parts



The first four digits will be followed by a hyphen, and then there will be a string of numbers, some having a letter thrown in just for fun, and then another hyphen. The stuff between the hyphens is what's called a group number. This tells you what the part is. 6015 between the hyphens means that this is an engine block. This might seem a pretty trivial bit of information to the person that is looking at the engine block, since they're looking right at it, but, to the people ordering the parts from the plant making them, which also makes a bunch of other stuff, it is very useful. On many parts, the casting number will not include the group number, because the person looking at the the number on the part would know up front that they have a carburetor in their hand. There's no need to stamp the 9510 on the carb just to make sure that the person with the gasoline dripping into his hand realizes that this is not a front bumper, but, a carburetor. The engineering number will have this, as will the replacement part number, though. The person at the warehouse processing the order has no idea what it is that I need.



After The 4-digit prefix, the group number, and, the second hyphen, there will be a letter. This letter indicates the design change level. That means that they started with a part, say, C5ZE-9600-A, which would be a breather assembly. They then change the design to include a fitting sticking out of the side of it. It becomes C5ZE-9600-B, they change the design again to put a longer, stiffer spring on the snorkel flap. It is now C5ZE-9600-C, and so on. This is purely for the sake of example, and are not actual design changes that are represented by these specific numbers. Let's say, for example, that I am needing a rebuild kit for my 2bbl carburetor, but, I am not sure if it's the original carburetor for my car, and, the I.D. tag for this carb has vanished in the haze long ago. I look at the driver's side of the carb, and, lo and behold, there is something stamped there on the base, near the front, and it says 6 D F. Clearly, this is not the entire part number, so, I will need to start filling in the blanks. I can tell that this carb is an Autolite 2100 from looking at it, so, it was built sometime in the sixties. That gives me C6 D F. I also know that, since this is a carburetor, the fourth digit will be an F, so, I now have C6DF F. Again, since this is a carburetor, the group number will be 9510, so, that gives me C6DF-9510-F, and, that is the complete part number. If my car happens to be a 66 model Mustang that came with a C4 automatic transmission and the thermactor system, this is the correct carburetor for that. The replacement part numbers and the engineering numbers will have the entire number, while, the casting number will frequently leave out the stuff that you can easily deduce by looking at the part itself.