Straightforward. You have to drop the lower unit, the only tricky thing here is corroded bolts (don't force them) and the water pickup tube ( it has to align on assembly, self-explanatory). When assembling, twist the impeller in the water pump housing in the same rotation direction as the old one, and use plenty of grease on the bolts during assembly. Make sure the water pickup tube is clear and bolt up the lower unit. It is a great DIY project, take your time and use OMC grease or trailer bearing grease for assembly.