You are going to have to do the "leg" work yourself, at these site, to see if you can answer your questions:
3-11 HP
http://www.cpdonline.com/692509.pdf
http://www.tecumsehpower.com/framese...uals/index.php
http://www.smallenginesuppliers.com/...ine-specs.html
Tecumse (and Briggs) made basic engines, however Ariens may have had them make some changes, to suite them. You are not going to really know what is different, if anything, until start on it.
BG