or -- may reasonably believe kits or diaphragms aren't available.
If looking specifically by year, some online sources don't seem to list a diaphragm or kit for the '79. But the same pump number was used in later years, and the same diaphragm was used into the '90s (on models other than the 25 as well -- same diaphragm listed for a '91 9.9 when I needed it). The OEM diaphragm number for the '79 pump F_R cites would be 0332678.
Anyway, Jackman -- big pump and an easy rebuild with parts available. Might look under mid-'80s models for diaphragms and kits, matching up to the pump part number F_R lists to be absolutely sure. Or just search under the above diaphragm part number. And the aftermarket kit WIMuskie cites undoubtedly will be fine too.
(Although..... price on that pump seems to be comparatively good too, if you want to just replace it -- IMO)
