I can tell you from living in Renton WA where the plant is that things have changed slightly. I work out at an LA fitness where they used to hang the engines on the old 757 line, get my starbucks where the wings used to be attached, and buy home supplies at Lowe's where the paint shop used to be.

Now it's less building and more assembling. 73's show up mostly put together by rail, the wings from somewhere else, they are mated somewhere and a Boeing decal is put on under the cockpit window.

I think the 757 line is loooonnnggg gone.....