Found it, thanks! On my Win 10 laptop they are in c:\Users\<me>\AppData\Local\Arduino15\packages\teensy\hardware\avr\1.58.1\libraries\...
I installed the Arduino IDE for all users, but the teensy extensions got installed under my user profile...
I just updated from Arduino IDE 1.8x to 2.2.1, To install the teensy tools you enter a .json URL. I cannot find the teensy libraries anywhere on my local drive, so I assume they are now stored in the cloud?
@PaulStoffregen Glad you got the forum back. I'm sure that was a pain.
I really appreciate the quick reply on this. The insight for me was that I did not need to install Grieman's SdFat library.
I uninstalled it and removed my mods but the...