All information below was previously part of www.roadkillontheweb.com and was written by Lee Exline, National DeSoto Club.
DeSoto Diplomats - A Foreign Affair
The subject of Desoto Diplomats needs to be split into a few different categories:
Made in Detroit
Some DeSoto's built in Detroit were built on the Plymouth assembly line! They were marked as diplomats and had Plymouth bodies with DeSoto trim and nameplates and were included in the Plymouth serial number sequence; I do not know for sure when they started producing them the earliest literature I have on them is a 1949 piece from Hawaii. I have also seen pictures of a 61 that was based off a Dodge station wagon in Europe. This made for some very interesting cars since DeSoto quit making station wagons and convertibles in 1959 but you could still get 1960-61 diplomat ragtops you could also get station wagons and on the other end of this the last time you could get a regular DeSoto three widow three passenger business coupe was in the first series 1949 S-11 (looked just like the 46-48) line. After that they always had the small quarter windows, but you could still get a diplomat 3-window coupe in 1949-52 they used the Plymouth body with DeSoto trim.
From 1956-58 you could even get a passenger car based DeSoto pickup, but only in Australia!
DeSoto Diplomat's were built right across the border from Detroit in Windsor, Ontario, Canada and not only sold around the great white north but to many other places around the globe. Plodge's and Plysoto's.
Unlike a lot of the other diplomat markets, Australia actually built its own cars. The base model 53-54 Plymouth was used to make the Plymouth and DeSoto diplomats with only minor changes in the trim to distinguish between them. The 53-54 body style continued until 1957 down under until a modified 56 style was introduced. They also offered body style that were not available in the states. Most notably, the UTE that could best be described as a El Camino that they were making long before Chevy introduced theirs in 1959 and the ford introduced the Ranchero in 1957. They also made panel vans based on the passenger car chassis that were not available in the states. Of course the steering wheel was on the wrong side of the car also.
South African Built
Desoto Diplomats and Desoto Rebels were made at the South African Chrysler plant up until 1964. That's right, you could buy a 1964 DeSoto passenger car new off the showroom floor. The 1962 diplomat was based off of the 1962 Dodge passenger car and were probably assembled in Africa after being shipped there CKD "Complete Knock Down" with all of the basic parts disassembled and shipped down in stacks to be assembled there. The 1963 and 1964 models were based on the Plymouth Valiant chassis. Both were right hand drive! The literature I have on the 1962 DeSoto is written in a South African version of Dutch. I have seen pictures of a 1963 Rebel in a collection in South Africa but have never seen a 1962 version in images other than literature.
Why didn't they just get a good old American made Desoto?
Foreign countries commonly specified to manufactures that there be a notable difference between the models that were legally imported rather than smuggled in without the government getting their fair share. By changing the name, it made it easy to determine what cars were there legally. and on some occasions there were high import duties set by the governments against American made goods. This is the case with Canada and Ausrtalia! I found this piece of information on another site that explains why (it does have some errors though - Chrysler Australia offered a V-8 in 1957):
Following the end of World War II, Australia, like all Sterling based countries, legislated to restrict the use of US Dollars which were in desperately short supply. As all Australian petrol was imported (in US Dollars) petrol rationing continued after the end of WW II and the use of US Dollars to import cars required a government permit. Therefore, only people with access to US funds held overseas, such as consular staff and visiting entertainers, could bring American cars into the country. There were many instances of Americans based in Australia importing a car (quite legal) but under an arrangement with an Australian citizen to take over the car once in the country (not legal). Detected occurrences of this activity resulted in the cars being seized by Australian Customs. Whilst it appears that Hudson, Nash, Packard & Studebaker distributors were able to obtain a quota of US-built right-hand drive cars, Australians wanting one of the Big Three's products had to obtain it via Canada. US car manufacturers had subsidiary plants or divisions in Canada (British Commonwealth) and these plants manufactured export models, including righthand drive, for export to various countries including Australia. Waiting lists stretched for years for most makes. Pontiac, Chevrolet, Buick, Oldsmobile, Chrysler, DeSoto, Dodge, Plymouth, Hudson, Packard, Studebaker, Nash, Mercury and Ford all appeared in agents' showrooms around 1946-47. These cars were all 4 door sedans (except Chevrolet, Mercury & Ford who also offered Australian-only Utility versions) and were of basic configurations only - no heaters, no automatic transmissions and no radios. In contrast to this, leather upholstery which was only available on the better models in America was common on the Australian version. In 1948, Holden began locally producing "Australia's Own" car. Holden is the brand name of General Motors Holden Pty Limited. The car was an immediate success and demand far outstripped supply for some time. In the fifties cars such as Buick, Oldsmobile, Mercury & Chrysler had disappeared from the showrooms and prices were rising for those cars still available. During 1951 there were 121,000 new cars registered in Australia with the majority (74%) coming from Britain and Europe. Holden's share was 18% leaving only 8% being from North America. In 1955 Pontiac was the first to rival to Ford in having a V8 available in Australia. Chevrolet followed in 1960. The currency restrictions were withdrawn in late 1960 and although this opened the way for imports direct from the US the arrangements via Canada continued for Pontiac and Chevrolet.