The low speed bus that deals with the cabin buttons? I was wondering the same, but I tested the circuit and got 52 on the reading, I can only assume that means there is a resistor on both ends.
Yeah, to get the 29-bit version to compile, copy the libraries folder out of the download and put it in the root of the documents Arduino folder - won't have any problems compiling then.
For 83kbps support, I copied the hard coded values from the master branch;
// Hard coded configs
config1 = 0x03;
config2 = 0xBE;
config3 = 0x07;
And place them above the 'digitalWrite' functions in CANBus.cpp (Line ~205). Do this before copying the libraries folder.
I hope this helps. It turns out I didn't need the 29-bit functions, now I am just having all sorts of trouble trying to write text on my speedometer (under the Audio page). Deciphering what the original stereo sends isn't working as well as I thought it would.