Well, you might be looking, but they
DO NOT EXIST!
17 and 19 inches are all 5:4 as they are 1280x1024 pixels (or 16:10/16:9 since recently)
You need 20 or 21.3 inch. Those sizes are available in 1600x1200. Big plus: they are all S-IPS or S-PVA so better image quality.
15 inch was available in 1024x768, so that is another 4:3 option.
Cheap-ass solution: there are 4:3 TV's with 20 inch LCD's with 640x480 or 800x600 resolution, but O BOY there is bad TN panels in them.
Forgot to read you post very well: You talk about VERTICAL placement. That makes things even worse. There is no escape! You have to spent more bucks on a SPVA or SIPS panel. TN looks ---steaming pile of meadow muffin--- mounted vertical. Check out a second hand
DELL 20 or 21 inch with 176/176 or 88/88 viewing angles or better, or a Samsung 213T or a 214T. HP also has some old nice 1600x1200 displays. And there is the Eizo S2000 and S2100. This segment is probably your only hope.
Well, now I look at it, the Dell is a good deal. You won't regret that panel.