Originally Posted by TEM48
I'm looking for a diagram of the frame showing tanks and other vital organs to avoid drilling something that I shouldn't when securing the new brake lines.
To answer that question, I don't know of a published diagram that gives the layout on any of the units.
As I have not seen a Excel 26TRW, I can only refer to MY unit and you can check to see if they are similar. If you are planning on drilling into the bottom of the frame from the front compartment to the area forward of the axles, you should be ok in doing that. On MY unit, and possibly yours if the 50 amp power plug is in the rear, the 4-wire 50 amp wire bundle enters the frame at the rear and exits just forward of the front axle, where it enters the basement and routed to the electrical breaker panel. If unsure you should check with PI on its routing. Other than that short run, MY frame is what you see and hollow inside. The spring shackles are attached to an additional tube/channel that is welded to the bottom of the main frame rails and should be hollow and allow clamps/holddowns to be attached.
As an option to drilling the frame to go from the front to the axle area....the underbelly fabric is attached to what appears a 2x2 wood frame that runs front to back and is screwed to the frame . You should be able to feel it as you rub/push on the fabric as it attaches to the frame area. Should be able to route yours lines along either.
Hope that helped.