There were no clips on the bottom of the cab behind the one on the toe-board on my '51. I didn't find a grommet underneath the cab, and believe the wire just went to the inside of the frame channel. The FAM Section 12 Sheet 15.00 shows the various wiring clips that go in the holes in the frame, then a grommet in the rear crossmember and finally a bolt-on clip just before the end of the frame. The FAM shows the 54 configuration of the rear crossmember as a C shape facing forward with a single vertical part, while the earlier years have a crossmember with a "hat" shape. There's a hole in front and back of the vertical parts of the earlier crossmember, so that would lead me to assume that two grommets were necessary.
