This is what my PA40 Ultra Lite looks like. If it helps?

From another post by Randy,
The PA 40 is the same size case and mount diminsions as the 51, 61, 65.
 They can all be  interchanged, with each other. And ALL PA engines run very well on a pipe or muffler.
The new Merlin series PA ultra lite 40 is a much smaller size case and will go into many classic airplanes as well as modern stunt ships.
It is more the size of a 35 engine.
Weighs about the same as an Aero Tiger or Magnum 32, 36  (8oz.)
The PA 40 Ultra lite has the same mounts as an older ST 35, 40, 46, but is longer on the nose. This allows you to make a very sleek cowl without using a prop shaft extention.
Regards
Randy
Click on picture to see it larger.