Years ago, I had a 1953 WE 500C telephone. It was black in color. I used a 1973 WE 500DM phone I found in some trash as a donor phone to add a dial to the older one. The donor phone was black in color as well.
Before I removed the dial, I made a crude diagram of where all the wires went. I noticed that the brackets for the dial on the two phones were different, but that didn't seem to cause any serious problems. After installing the dial, I successfully called one of my neighbors and asked him to call me back. When he did, I heard another phone ring, but not the one I just installed the dial on. I answered the phone and told him I now had another thing to work on.
I later had both phones opened up trying to figure out what else I needed to do. I then noticed that one of the ringers wires on the donor phone was in a different spot than on the older phone. In short, moving that wire made the ringer work again. To this day, I have no idea why adding a dial to a phone would require a wiring change to get the ringer to work again.
The donor phone went back into the trash, minus its dial of course. I would've kept it, but the handset cord kept falling out of the handset. Changing ends on the handset cord didn't help one bit. Oh well, I got a free dial out of the deal.
Back then I had no idea that there were different networks among WE telephones. All I remember is that the networks on both phones looked an awful lot alike. It may have been a miracle that I got a newer dial to work on an older phone, but I did.