In Reply to: 9N posted by abraham brower on November 03, 2020 at 07:56:06:
A letter after a part number denotes a revision: “A” would be the very first part as released. When they made a revision, the original became the “A” version then the revised part carried the “B” suffix denotation. The added numbers following the p/n denoted a different supplier. Some examples are the original 9N-10000 Generator used on the first early 9N’s. It was a 2-Wire/2-Brush, 7-AMP, B-Circuit Type unit that used a Voltage Regulator. In early 1940 Ford revised the generator to the 9N-10000-B version and then the first one became the 9N-10000-A version. The 9N-10000-B Generator was a 1-Wire/3-Brush 7 AMP, A-Circuit Type unit that now used the roundcan cutout. You can search MPC’s to see all this info and note the cutout was now a different version as well. Also worthy to keep in mind that the letter suffixes after a part number are NOT the same as the ‘A’ and ‘B’ Circuit Designs; they are two totally different animals. As far as the added numerical values to a p/n, when two or more suppliers are used, each is numbered to denote which is which. A perfect example is the early Ford-Ferguson 9N tractor air cleaner. As was Ford’s practice, many parts were farmed out using outside sources. The air cleaner for early 9N’s had two units that could be used. One was the Donaldson and the other was the United. Part Number 9N-9600-C1 was the Donaldson supplier, and p/n 9N-9600-C2 was the United supplier. Either could be used and were used when part availability for one was depleted and the substitute 9N part had to be used. Ford didn’t like to stop the line, any line, waiting for a part supplier because they couldn’t keep up with demand. MPC’s on early 9N’s had a list in the back of which air cleaner was used based on serial number. Hope this answers your question.