for less than $14, and fits nicely in any kitchen junk drawer
https://www.amazon.com/ALLOSUN-Digit...%2C103&sr=8-23
the idea behind the 3-wire signals is that you'd run an additional wire from the front turn signals to it for switchback functionality. you might only be able to attach one wire, as the other might be disabling the main lighting function.
i've never wired/re-wired the side marker lights on my car, so i don't have any additional feedback on how they work.