I wrote it down as as a HH170 -140055E. The tiller is so old it does not show up in Ariens parts. (901006) The motor is cast iron, horizontal shaft, and has a counter-rotating output shaft run off the camshaft. This output is used to reverse the tines when engaged. The air cleaner is mounted vertically instead of horizontal. The engine is set up to have an electrical starter. You are right it is a beast of a tiller. the way this tiller is made would probably cost $3000 to $5000 in todays economy. Thanks for all the help so far.