Jet kits come with all the hardware you need to convert your motor to a jet. (You will need to use the water pump off of your existing lower unit.)
Notes about this kit:
Rear base of engine mid-section – compare shapes 
Add $160 for 6 1/8″ stainless steel impeller upgrade, #1737.
For use on – 40HP, 50HP, 55HP, 60HP Johnson/Evinrude 2 Stroke Motors