Zinc on a 1977 Johnson 35 hp Seahorse

"I have a 35 hp 1977 Johnson S

"I have a 35 hp 1977 Johnson Seahorse. I recently rebuilt the lower unit. The used lower unit housing that I put on has some chipping paint. Do I need to install some zinc on the cavitation plate to prevent corrosion? Where is the best place to install Zinc in this situation? I use the boat in salt and fresh water. It is not stored in the water, it is trailered and kept on the trailer... We always flush with fresh water after using in the salt water. Do I need Zinc if it is not stored in the water at a dock? Any help would be much apprecieated on this topic.

Thanks,

Mike"

"If you have a swivel trim tab

"If you have a swivel trim tab on the lower unit, it is zinc.

IMO it's not work puting a sacrificial anode on the motor if you pull it out after use and wash it (don't just flush it, wash the outside). The anode is necessary if the boat will be sitting in the water for long periods of time."