I am lucky enough to get my hands on a Realistic TRC-86, the walkie talkie they used in the series. Not sure if it works but just to have as display is
Old Realistic TRC 214 CB walkie talkies - YouTube
Realistic TRC-214 Handheld CB Radio Walkie Talkie for sale online | eBay
ArtStation - Stranger Things Realistic TRC-180 Lucas' walkie talkie.