Yea Merc, I believe they should bolt right up! But go ahead and measure the motor mounts and make sure the holes are the same, just to be sure! Both these engines list the "Distance Between Mounting Holes Same Side" and "Distance Between Mounting Holes Opposite Side" (As well as some other measurements you can double check against your motor/motor mounts) But your going to have to use your flywheel, clutchbell/clutch, and clutchnut from the SH18, as the new motors come just as pictured.. And your drivetrain should be fine with either of these .18 engines as well.. They'll give ya more pep, but the biggest difference between the SH and these, is these are better built with better parts and will last alot longer if ya break em' in right and treat em' right..