Stephen,
There are several and the locations depend on the cooling system used. If it
is a heat exchanger or keel cooler, the fresh water magnesiums are in the
expansion tank casting on either side. On heat exchanger systems, the
sal****er Zincs are in the tank to element adapter castings on both sides
where the salt water enters and leaves the exchanger. These will appear to
be 1/2" pipe plugs.
Steve\

"Stephen Scheiding" wrote in message
...
can anyone tell me where the engine coolant sacrifical zincs are
located. i need to change mine. model gm 6-71n, marinized by johnson
towers.
thanks,
stephen scheiding