Not that hard at all. Remove engine cover, look where the shift lever goes into the side of the casing, move the shift lever up and down, F-N-R and see where the linkage is held together with a short pin and cotter pin. Remove cotter pin, pull out the small pin. Tilt motor up, remove the four bolts under the cavitation plate. Now with a bit of luck, the lower unit should slide down, it may be persuaded with a rubber hammer. Once the lower unit is off, you'll see two long shafts, where they enter the lower unit, theres a cover with 2-3 small bolts, remove the, lift off the cover and the impeller is underneath. STOP, look which way it's in there, some have a little flat spot on the shaft. Get out the new impeller, apply a bit of vaseline to the wings or fingers and a bit inside the housing, replace the impeller, replace cover, replace bolts. Now at the top of the splined shaft, clean it with a steel brush, apply anti seize. Now comes the fun part. When you slide the lower unit back in, you must aline the shifter rod, the splined shaft and the tube that goes up for the water cooling for the engine. Replace lower unit bolts. Replace the small rod and cotter pin for the shift linkage. Now if all was lined up correctly, place the shifter in F or R, slowly pull the motor over, the prop should turn either forward or back, In N, it should free spin. Get out your big garbage can, fill with enough water to get about 1/2 way up the leg of the motor and give it a start, water should start peeing out within a couple seconds. Done. Good luck. Bolts are metric, most likely 12mm, the impellor cover bolts might be 7-8mm.