The Care And Feeding Of Ponies

The Care And Feeding Of Ponies

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. Here's how that works. The first digit will be a letter which signifies which decade the part is from. 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. The fourth digit is telling you what sort of part it is in a very general way. 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. 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.

With Ford's withdrawal from Trans-Am officially following 1970, the high end Boss 302 and 429 disappeared and were replaced by the large street-oriented Boss 351. The 1971 Mustang was larger in almost every dimension, earing the nickname the "Clydesdale". In 1972 the 429s were dropped from the lineup, and horsepower dropped across the board. This year also produced the fewest Mach 1 sales of the 1971-73 generation. There are no major differences in the 1971 and 72 Mustangs externally, other than different script on the trunk panel. In 1973, the Front end was changed to fit new bumper standards, and a new Mach 1 grille was made. The Mach 1 grille in prior years had 2 "sportlamps" horizontally across the grill on the left and right side, while the functional parking lamps rode low underneath the front bumper at the outer ends of the valance panel. In 1973, all Mustang models had the sportlamps changed to a vertical orientation at each end of the grill, and these lamps served double duty as the parking lamps also.

This was necessary since the new-for-73 front bumper was larger and effectively blocked the view underneath the bumper, the previous location of the parking lamps. The rear bumper was also mounted on new bump-absorbing extensions which caused the bumper to protrude from the body about an inch farther than before. The Mach 1 graphics were also updated to a simpler, yet bolder design, which was necessitated by the change in the front bumper. Engine options remained the same as in 1972. One of the most recognizable as well as popular features of the '71-'73 block-off plates in the scoops, so it was a visual, non-functional item. However, they could be made fully functional on models ordered with the 'ram-air' option. This included vacuum controlled 'flappers' at each scoop, and a huge fiberglas underhood 'plenum' that directed cool, outside air into the carburator for increased performance. The ram-air option included a two-tone hood paint treatment in either 'matte black' or 'argent' (matte silver), coordinated to the color of the Mach 1 decals and striping. In addition, all ram-air equipped Mustangs of this generation came equipped with big twist-style chrome-plated hood lock pins.