http://www.corvetteradios.com/Page7.html
Here is a website where you can buy those little Delco LED's. They are a bit pricey at $2.00 each, but they are the same factory Delco OEM LED's. They also have the radio main display bulbs too.
I've never replaced the radio LED's, so I don't know how to replace those..... but the main display bulb was easy though. There are also some photos on the website. Hope this helps.. Take care everyone.
Tommy