They need to know the diameter of the heat exchanger. You can't mix them up because the larger won't fit. But you can screw up the tubes inside the heat exchanger if the zinc is too long. Then hack saw the zinc off to match. In high saline conditions or year around use, I'd check the heat exchanger zinc at least twice a year.
Zincs are cheap.
Inc. Additionally, this material has not been reviewed by Catalina Yachts, Inc. for technical accuracy. This page's maintainer cannot guarantee the accuracy of this information or the desirability of suggested modifications or upgrades. Please obtain assistance from a competent marine mechanic or boatyard prior to making any significant modifications to your vessel. 185 visitors since May 15, 1997. Last modified by Bryan Pfaffenberger , June 19, 1998.