Glad you guys caught that for me!! I have found the Tony Gregory 4th edition book to have more than one error. Here is the text from Gregory, copied and typed exactly, including all the improperly inserted commas.
What he wrongly infers is that all C6OE-A pumps came without the 6 vane Hipo impeller. He stated elsewhere in the back of the book that L-8 occurred at May 1965-August 1965. The water pump section has some accurate info and some inaccurate. Again thanks out to Jim and Bob for correcting this.~Ray
"High performance 289's built before August '64 use aluminum pumps with part numbers C3OZ-8501-B, and casting number C3AE-D, or C4OE-A. After August '64 part number C5OZ-8501-A, and casting number C5OE-A were used. At change L-8, C5OZ-8501-A, B cast iron pumps with casting number C5OE-A, B replaced the aluminum pumps. Mustangs of 1967 vintage, and service replacement, employed a standard 289 pump, with part number C5OZ-8501-C, D and had a C6OE-A casting number. Author is also in belief that if a HP pump was not handy, at any point, during the engine building process, a standard pump was fitted. Water pumps were painted engine color on '65-67 engines but author believes a few 64-1/2 cars slipped through and were left natural. It should be noted that the timing cover changed at L-8 with added support for the heavier cast iron pump".