Has to be 5906. Everything else is a variation of it, be it size, caliber, construction, specialized usage etc.
this isn't necessarily the same thing. Lots of people "must have" the smaller CCW versions (6906 etc), others a different caliber.

Consider 3rd Gen the way you consider "1911"... ICONIC would be a milspec, 1911A1, with blue or parkerized finish, 5" barrel, .45 acp.

You can get a 1911 in any caliber, in varying barrel lengths, with aluminum frame, chromed, stainless, cerakoted etc. Grooves all over the slide, rail if you like, ambi controls. Might be your "must have", but it's not the "iconic" version.