With the 5x7 matrix LED display. The is a LiteOn unit, yellow, LTP747KY. I got it from Digikey. It's the smallest 5x7 matrix LED I was able to find there. I wish I could find smaller.

After squinting for about 15 minutes at the LED top and bottom I wasn't able to find anything that indicated where pin 1 was — some vague clues, but nothing like an arrow or dot or dimple that you might expect to find. So, rather than soldering the device in place, I just put it through the holes, which are plated on the inside so they're conductive. The fit was so tight for each pin that I expected the pins of the LED would make contact with the through-hole. Once I determined that I had the LED rightside up or upside down, I would then solder it in place.