[Accelo]

Here is one with the 6 cylinder that gives some decent detail.

After a lot of research, none of which I could really confirm, I believe there were a lot of factory configurations. Some depending on the build plant and the motor transmission combinations.

I know some of the general differences at the front cross-member. The lines are in front of the cross-member on the disk brake trucks and behind it on the drums.

The attachment point at the differential is also different in 72. The steel line ends at the RH frame rail on the earlier trucks and continues to the center of the differential along a frame cross-member in 72. Don't forget the combination valve is different between the disk brake trucks and the drum trucks.

Frankly the darn brake lines were one of the biggest headaches on my build. What I purchased either didn't' fit or leaked. The third proportioning valve finally worked and didn't leak. I ended up making most my lines. Only thing I did correct is use DOT5 fluid. It doesn't remove paint, when it leaks, and my system leaked everywhere. Very frustrating experience. Did I tell you I hate brake lines? LOL.