That looks like a better adapter and it's Rad-specific. It's not as along as the one I found. Thanks for the info and the link!

Side note - this took days to gather all this info between the time Rad and Burley responded and doing the research and finding that video so I hope this info is helpful to others.

Hi Dan,
Thanks for the recommendation.

Both Burley and Rad said they cannot confirm anything because they haven't been tested together. (This was before I posted here). Rad gave me the specs of the axel (wasn't online, so had to email to get them). Burley wasn't able to confirm anything - just specs and that you need space for a 4mm hitch. THe Rad Bike axel doesn't have that much space so it needs an extender.  I called REI and they were the most helpful in that the said  Burley and REI did not have anything that was compatible. So I continued looking online. I found this video: https://www.youtube.com/watch?v=ghk6Ikgp69E&t=641s which as the most helpful as it described exactly the extender I needed. AND it gave me the link to order it, which I did.  I'll post here for others after I receive on my experience. I hope it works!

RadRover Bike Axel specs:
Axle size: 12 mm diameter, 10 mm flats
Axle thread pitch: 1.25 mm
Axle length: 226 mm

Extender for Rad Bike and Burley Tail Wagon: https://www.mcmaster.com/92499a775/
Video explaining how to hitch and what you need: https://www.youtube.com/watch?v=ghk6Ikgp69E&t=641s

Hi, Has anyone here had experience connecting and using the Burley Tail Wagon with their RadRover? If so, can you please let me know what you had to do to make it work? Did you need the extender? Thank you!