The 42 was from a Poulan Pro 260, I picked it up at Lowes last winter for $89.95. Basically, you have to modify the Hanger Nine mounts a little to fit, make a prop adapter, design and fabricate some kind of mount for the pulse switch (pickup sensor), find TDC and install the magnet in the right place so it fires at 28* BTDC. C-H makes a bolt on conversion kit for this line of engines if you don't have the skills or equipment to make the parts yourself.