Richie,
Tara wagon without hood 28mm high from the base (of the wagon & not from rail level!!!) of the bufferbeam/ 32mm wide x 128mm long chassis (excluding buffers), 6mm high bufferbeam, 2.5mm gap, 8mm to brace, brace 1.5mm, 3mm from brace to high beam, beam 7mm, top of wagon 34mm wide(brace 1mm width either side.
Tara roof 3mm thick x 34mm wide x 130mm long(flat roof) has 40 bars across the top 1.5mm wide, gap 1.5mm
Gaps between braces on wagons vary between 10mm to 13mm wide.
The shale wagon differs with the horizontal strengthening bar is between 1.5mm & 2mm thick, height above base approx 9mm with the next horizontal bar(smaller to the side) approx 1.5 to 2mm higher up.