Hello Manu Mach1,
Unless you have dealt with the Ford numbering system on a regular basis, the use of engineering numbers vs service part numbers can be a source of confusion. Ford NEVER stamped, molded, or printed the actual part number on any part. What you see on the part is an Engineering number which was used both on the assembly line and at the Consumer/Dealer level. This was a way of helping to identify a part where there may be several that look the same but have functional differences.
Some clutch forks may have 7541 or 7515 but will cross to the 7515 which is a service part basic number.
In your case, the engineering # C8AA-7515-B crosses to the service part number C8AZ-7515-B. So both numbers are for the same part. The C8AZ means that the full-size Ford powertrain engineers were given the responsibility for the design of these Forks.
C=Decade, in this case, 1960's
8=Year of release, in this case, 1968
A=Model or product line originally released. in this case the full-size Ford
Z=Engineer office responsible for the release, in this case, a service part
The letter after the basic number is usually a design or revision level. With this part, "B" just happened to be the next letter available since "A" was already in use for the C8AZ-7515-A which was the full-size Ford with 427,428,429 engines.
I hope this is not too much number overload!
