RWD axle, with disc brakes. A reciprocating saw and some good quality bimetal blades, followed up with an angle grinder helps with the difficult task of removing the stock brackets. Brakes can be swapped side to side, which moves the parking brake mechanism and cable to the rear out of the path of the trailing arms. This requires that trailing arm bracket be mounted at the front of the axle, different from the book version (see below).
Axle brackets need to be placed on the front of the axle, opposite to the book design, as there is not enough clearance around the brackets for the disk brake calipers and parking brake cable. An alternative might be to leave the brakes at the front and separate the trailing arms further, I didn't try this route.
Brackets were made by trimming a 6" length of 2"x1" RHS. This thinner tube is somewhat easier to fit on the GTS axle thanks to it just fitting inside where the axle tube changes diameter. 2" was cut from the top and bottom of the front of the bracket for the trailing arms, while the 2 1/2" diameter semi circle was cut from the rear. 31/64" holes were drilled 1" in from the front of the bracket (reamed to 1/2" once welded in place). This leaves the bracket pretty much closed all around, adding to it's strength.
Flush with inside edge of M1/M2. Find correct height from table, tack into place. Mike Laws substituted M1/2 square tube with channel of the appropriate size to hold the trailing arms, eliminating the need for separate brackets. In my case, a 1" walled, 1x2 tube would have worked well.
Set perpendicular to center line, ensuring hubs are an equal distance from the RU's and an equal distance back from the M's on either side.
Center the axle in chassis to mark the side to side bracket locations. Use a straight edge from chassis brackets on M to find best location of brackets on axle. Then use a long straight edge clamped the to pinion output, flat on where the u-joint attaches. To align brackets perpendicular to horizontal verify equi-distance from top/bottom points on both brackets. Do this by hanging a square from the straight edge, and pivoting it on the pinion over the brackets.
To make it easier to align the axle I decided to use full spherical rod ends on the rear trailing arms. You can see spacers positioning the trailing arm in the center of the brackets, which were originally designed to hold bushes as per the book. It would be possible to use narrower brackets on the chassis side, with the new design allowing for careful positioning of the trailing arm to clear the chassis and a new location for the brackets on the axle.
My trailing arms are about 10" c-c of the rod ends. This contrasts with Ron Champions design, where the trailing arms are 12" c-c, the difference due to the brackets in my design being placed at the front of the axle. You should place the axle at it's desired location in the chassis and build the trailing arms to suit.
Unlike the trailing arms, I used high strength 1/2" spherical rod ends on the panhard rod, using L/H and R/H threads (along with the apropriate threaded tube inserts) to allow for easy adjustment. Short 2" lengths of 1"x2" rectangular tube, were used to allow attachment of the rod to the chassis and axle. Here's a photo of the axle side bracket. Note that the panhard mount sits just above the spring on the brake, and attaches to the axle at the bottom. It serves as one side of some gussets that were added later to the shock brackets. Here's a photo of the chassis side panhard bracket. You can also see the l/h shock bracket. Gussets were later added to that bracket as well.
I inset the upper brackets by about 1/2" on the 4"x4" shock mount. This is likely unnecessary and did make welding the bracket a little more difficult. Lower location was found by dangling the shock to the bracket. I tilted the bracket slightly toward the front to match the slight angle of the shock.
