On May 12, 1955 C.A. Watson, General Sales Manager of Willys Motors, Inc. sent a 2 page letter out to all distributors and dealers holding Willys franchises. He indicated that due to the profits generated at the dealer and distributor levels on the "utility vehicles" (jeeps, trucks, station wagons, etc. rather than passenger cars) the factory would be concentrating on merchandising the "highly specialized and non-competitive utility vehicles". This may be the closest thing to the kind of letter that you are looking for.
Normally, at the end of a final model year for a product, no official statement from a car company that a brand (like say, the Frazer) would be discontinued until the end of the year. It was felt that letting dealers know during the model year might put a damper on efforts to sell off the remaining affected new cars a dealer or distributor might have. If a dealer wanted a particular new car, there were ways, through the proper channels to see if a suitable new vehicle could be found from another outlet. One such case involved a dealer need for 5 new 1951 Frazer Vagabonds for a fleet sale. The activity is documented in a KAISER-FRAZER DEALER NEWS article from the late summer of 1950.
Ford and Chrysler Corporation sort of broke the mold on the policy with the 1960 Edsel and 1961 DeSoto. They issued the announcement after dealer retail delivery reports indicated that the entire production run of qualifying cars (demonstrators included) were gone. GM made the biggest noise in this area when it shut down the Oldsmobile division by announcing the production plans for the last 5 or so model years of the brand.
If you find such a letter from Willys on the 1955 passenger cars, please let me know. I would like a copy for my archive.
