Re: Head Gasket needed
You can get SOME parts for the old OMC and Honda... not all of them.
Given that many OB models are available new for 10 or 20 (or more) years, if you then look at an additional 10 years, that makes a typical model run a whopping 30 years. That would never happen with a car or boat. Try to get genuine MoPar parts for your 1966 Chrysler Imperial.
Technology changes a lot in a third of a century... and OB's that run in salt will not last that long, so demand for service parts drops to nul. While it would be nice to get parts "forever", the reality is that OB manufacturers can't afford to have old, dusty parts dry-rotting on the shelf, or have the sub-manufacturers run a handful of "new" parts for them every couple of years. When demand for a particular part drops to near zero, the part will be discontinued.