WE 554s with 228A modular backplates: are they all conversions?

[MaximRecoil]

Or did Western Electric make some that had the 228A backplate straight from the factory?

At some point they started integrating the sliding 523A modular plug right into the actual base, so it didn't need an added backplate to mount on a modular wall mount jack. These—oddly enough—also retained their keyhole slots at the top and bottom, for the older hardwired method of mounting. These 554s were definitely modular straight from the factory. When did they start making them like that, and how common are they? Nearly all 554s that I see are either hardwire mounting style only, or have a 228A modular backplate.

It is frustrating trying to find information on 554s. Wikipedia doesn't have an article on them for example; they are just given a passing mention in the 500 article. Other sites I've found do the same thing. I know that they are fundamentally the same as a 500, but they are still a distinct model of phone, with a distinct application, distinct history, and distinct variations. I can't even find out who designed it (was it Henry Dreyfuss)?

The wall phone (usually in the kitchen, and usually a 554) was always the main phone in my house when I was growing up, and that was the case with most everyone I knew. In fact, my aunt's 554 was the only phone in her house for about 35 years. For such a common phone that saw so much usage over the years, it is strange that it tends to get relegated to the status of being a footnote in the history of the 500.

[paul-f]

It is frustrating trying to find information on 554s. Wikipedia doesn't have an article on them for example; they are just given a passing mention in the 500 article. Other sites I've found do the same thing.

There are still many opportunities for research in the area of telephone collecting.  Even if you find a wiki article, be suspicious unless solid, reliable sources are quoted.  Many opinions that get published in glossy collector reference books or spread on-line later prove to be erroneous.

Here are a few sources worth checking.

A lot has been written on the 554 in Singing Wires (TCI Journal) over the years, and in Old Time Telephones (by Ralph Meyer).  Many details may also be found in various issues of the BSPs.  Look for the C-series BSPs for the early history and 502-division BSPs for later production details.  Modular wiring started appearing in about 1974, so the early BSPs for the 554BM should appear around then.  You may also find announcements mentioned in employee publications or press releases from around that time.

I hope you'll share the results of your research!