When we purchased TD I had the backup raw water pump rebuilt. When the seal on the installed one failed and I replaced it with the backup the replacement pump lasted 4 months (sitting in a locker for 8 years). It was a good thing I rebuilt the one I took off first chance I got as I had to swap the new backup under less than ideal conditions in Central America.

Backup raw & freshwater pumps, very important. Backup starter as well as you can run an engine for a few minutes with a bad pump but if you can't turn an engine over to start it, it's not good at all.