Brent was a great help via the FB group, but I thought I'd try to consolodate some of the info here so it's easier to access when folks are searching.
First, I was running on older firmware on the MS3 and Tuner Studio, which didn't have some of the settings necessary available. I didn't realize this until I was able to look at a FB group discussion that contained some screen shots of the required settings, and noticed that I didn't even have the menus shown. So, the first step in getting everything working is updating to the latest software/firmware. Once I did that, I was able to get the settings burned to the MS3 and I was off and running.
This is the FB discussion that helped the most: https://www.facebook.com/groups/autospo ... 986502770/
This is the ASL Wiki for MS/CAN: https://wiki.autosportlabs.com/Megasqui ... ItJxwlOrZ0
Two values that are important, but not always obvious in the discussion are the BAUD rate for the data, which should be 500k, and the base message identifier value in Tuner Studio which is 1520.
Here's a screen shot of the TS Real Time Data Brocasting menu:
There is also a script for CAN logging that can help for diagnosing the communication: https://wiki.autosportlabs.com/CAN_Bus_ ... QNyH4M1jd4
If your Track MK3 is the only CAN device on the bus, my understanding is that you will need to set it to be the Terminus for the bus in the App settings. Since mine was sharing the bus with the PT gauge, I did not turn on the Terminus setting. Here is the way I have my setup connected:
Again, Brent was a great help getting this working, but I hope posting it here will make the info easy for folks to access in the future.