I’ll show you how to install a third brake light on your 2014-up RAM Promaster. While I was adding a 3rd brake light, I went ahead and upgraded the backup camera to a high resolution model that is compatible with my aftermarket Joying Android stereo upgrade. You can see how I installed the stereo here https://youtu.be/maLzT2HdSSo
You can buy the 3rd brake light I used here https://amzn.to/46v4W6j
The alternate flush mount one is here https://amzn.to/3NS0mb4
Backup Camera I used https://amzn.to/442GQyg
Aaron's Customs LLC 