Yes, that is correct. The 4 way switch will bolt right on, if you want to have the additional position.
Blewdy Yaink's explanation of how your 1971 model is listed as 1972 is almost correct. During the great depression, here in the USA, many auto makers were on the verge of bankruptcy. Fall and winter were traditional periods of slow sales for new cars. The horrid economic climate made things much worse. The manufacturers asked the US Congress to pass a law to allow them to move the start of the new model year from January 1st to the previous September 1st. This would help them generate car sales during the slow months. After the depression ended, the practice was continued. Many people would wait until September & October to buy the "left over" last year's model cars. These cars were brand new, but because everyone wanted the newest model, the manufacturers would have to discount these cars to sell them. The New model year in September practice did not extend to motorcycle sales.
Until 1975, motorcycle dealers were allowed to list the "last years left over bikes", as new. That allowed them to avoid having to "discount" them to sell that old stock. That is how your bike, manufactured in [probably late] 1971, got titled as a 1972. FYI, many 1971 models do not have the month of manufacture listed on the red certification plate, located on the head stock of the frame. My 1971 is one of them.
Does your bike still have the 1971 short side stand? The mounting lug on the frame for the side stand often would break off. It's one of the few issues on that year. Andover Norton does not sell the old style short side stand. They sell a repair piece to upgrade the frame to the new, longer 1972 & later stand. If you have the newer stand, odds are the old one broke off and was updated. In the USA, most of the country has E10 gasoline [aka petrol]. The E10 plays havoc with fiberglass fuel tanks. Many of them have been replaced with steel tanks. The 1972 models have a large crankcase breather that bolts to the rear of the crankcase. The large hole creates a weak point in the cases. Your engine's breather is located where the camshaft ends in the left crankcase.
Charlie K
Thank you, Charlie, for the additional details. As you mention, there was no standardization (indeed no requirement or definition) in Federal law for model year on motorcycles until US. EPA exhaust emission standards were introduced -- which was past The End in 1975. That left a chaotic web of varying state practice for motorcycle model year.
The kicker is that states required an importer to provide wholesale paperwork (called a "MSO" or "MCO" - the states couldn't be consistent on anything - Manufacturer's Statement (or Certificate) of Origin). This was a document that was generated by the importer that provided the basis for a state to issue the first "title" document. All of this in the 1970s was made more complicated by the fact that there were two different importing companies for Norton in the United States. The states required that these MCOs list a model year. OK, model year would be listed, even though the factory never built to model years (it had been practise in the UK to introduce specification changes in the early spring in order to get motorcycles to retailers for the "selling season" as good weather returned after a winter). And during the Commando days, there was a mixture, here's a matrix:
1968 - First production Commando -- Spring 1968
1969 - First production of "S" Model, limited production of "R" model, changes to Fastback -- Spring 1969
1970 - Intro of Roadster, end of "S" production, no real base-model changes -- Spring 1970
1971 - Spec changes; ignition switch moved from side panel, new harness etc., "SS" and "Hi-Rider added. January 1971.
1972 - New engine cases, twin roller bearings, "Combat" option, Interstate introduced, Fastback phased out - January 1972.
1973 - 850 introduced, 750 phased out. "A" variant for noise control phased in (rare). Spring - 1973.
1974 - Mk2 850, engine updates, changes for exhaust noise control. "A" variant for noise control continued (common) - January, 1974
1975 - Mk3 850 - January 1975.
There was a time when one US importer would "reissue" MSOs to dealers after the beginning of a model year. (Yes, it happened -- INMTU, YK???) That importer was under investigation by the FTC for a period regarding MSOs for another motorcycle brand and entered into a Settlement Agreement stating that they hadn't done anything illegal or unethical before and they wouldn't do it again.
With all this lack of standardization and consistency, I say that registration in the US to "model year" is a "legal fiction" for Commandos. The number on a title means nothing. The only way to describe the equipment build specification from the factory is to list production date -- and expect that many motorcycles in existence today are "bitsas".
(I am familiar with all of this as it was a part of my job duties when I worked for NV Corporation/NT Corporation in Duarte California in 1974 - 76,)
B. Henderson, NC -- USA Norton, Marston Rd 72 - 74, Norton Villiers Corp,/Norton Triumph Corp., California 74 - 76, Shenston Rotary Project 76 - 78.