Florence Knoll credenzas — thick metal base versus thin metal base  

I have an unmarked credenza (the teak/bronze credenza in the photos) which I hope is a Florence Knoll piece. Most Knoll credenzas have a "thick" metal base. By "thick," I mean that the horizontal frame and the legs are made of the same 1" square tube stock. My credenza has a "thin" metal base, in which the horizontal frame is only 1/2" thick with 1" square legs. This seems to be a legitimate variation since I found a couple of other examples with thin bases. (See the photos of the rosewood/chrome and the walnut/chrome credenzas.) Does anyone know whether these thin base credenzas were a separate product line (or had a distinct model number), and when they were produced? Thanks.
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