start from the rear and put the pump in place. Shim only the rear bolts to get the drive shaft to sit perfectly in the middle of the hole in the hull. Once that is done align the midshaft by placing in in the engine compartment and slide it over the exposing drive shaft. Tighten evenly. Lastly place the motor onto loose motor mounts WITHOUT the drive shaft coupler. Slide the motor back and make sure the couplers aligin on the top and the sides. Shim between the motor mounts and bed plates. Once that is doen you are all alighned. All you need to do is tighten the motor mounts, slide the motor fwd so you can insert the rubber coupler, then slid ethe motor back. Make sure the shims have move or fall out of place and tighten the 4 bolts into the motor mounts.