Also, for the zincs, some source/pricing info if interested:
Description / PN / Source / Price
Anode, Engine, Tecnoseal Magnesium - 2-13/16" Diameter / R-2M (Tecnoseal R2MG 2-13/16") / Boatzincs.com / 14.19
Anode, Propeller, 3 Pc collar, Volvo folding prop 3-blade engine D2-55, Martyr Magnesium Anode, VP 3PC Kit / 3858399M / Boatzincs.com / 18.25
Anode, Saildrive, 358407M Volvo Penta 130/150 Saildrive Split Ring Magnesium Anode / 358407M (3888306, 3888305M) / Boatzincs.com / 59.51
Anode, Side-Power, Aluminum Anode (SM51180A) / SM71190A / Boatzincs.com / 10.85
These are Magnesium (Fresh Water), however but zincs are also available.