[Richard Coutts-Smith]

Could'nt say whether that was the other, or the same one, although that pic is credited as the first prototype being shown at the 1956 FVRDE exhibition, which explains the veiwng platform in both photos.
As a point of inerest, at least one of these trucks was converted to duals on the back two axles, and these were all driven axles, with plans for the double chain set up on the back bogies(a'la Scammell)
As for the motor, perhaps someone has the software to enhance the plaque at the bottom.
Rich