This layout shows all the basic parts to make our chassis. Starting at the bottom left, we find the front crossmember, and above that the front frame horns. You saw us build the crossmember with the other one in Chapter 1, and we won't go through the frame horn construction as this was almost identical to the first pair - the only change being that they were made separately to the main rails.
The main chassis rails are next, with the front cut at an angle (about 6 degrees) where they will join the front sections. The four 1-1/2" holes are for wiring, plumbing, or whatever other access we might need. Because of the rear kick-up, the rails are shorter than standard, so the rear tapers are much shorter. We also saved some cutting by cheating on the tapers' start point - because the body is to be channeled over the chassis, we have started from the back of the cab, saving about a foot per side. At the rear of the rails are the kick-up sections, where we are using 3" x 2" box to avoid more sawing. It might be seen as more cheating, but in reality, if we were Z-ing an original chassis we would have to add some new material anyway. Just back to the left are two vertical supports - tapered from 3" down to 1-1/2" - that will support the front of the rear subframe. The remaining two pairs of tubes are to make up the subframe - 2" x 2" for the lateral members, and 3" x 2" to run lengthways.
The short rear tapers were made, as before, by cutting a wedge out of each side of the box section, then clamping the narrow part down and welding. The rear risers are welded at 60 degrees from horizontal, and the tapered subframe supports welded at right-angles to the chassis about a half-inch back from the back of the cab (at least, where it should be). The supports are 6" long, so the chassis will have an effective kick-up of 8".
Once the back sections were ready, we had to weld the front frame horns on. The main rails and the front sections were lined up, clamped down onto the chassis jig, and carefully TIG-welded together. That left us with two straight chassis rails.
Viewed from above, the chassis widens from 26" at the front crossmember, to 31" at a point just over halfway back, then continues at a wider angle back to just under 40" wide at the rear axle centreline. Our chassis rails stop short of the rear axle, and will be 39-1/2" wide at the top of the rear risers.
As with the other chassis, this step is simply a matter of making a 2mm pie-cut in each rail, and clamping the rail to the jig with the rear lifted up by 1-1/2". After welding, this springs up to 1-3/4", which is what we're after.
And now we've got our two rails ready: 3" up at the front, and a total of 8" at the rear, along with the channel-job on the body, will get us down out of the wind.