[bestgenman]

In my experience building generator set and power units, most fittings are SAE but not all.  It really is up to the engine manufacturer i.e., Cummins , up until recently , used 45 degree SAE fittings and hose with the AI designation whereas the AII hose and fittings used 37 degree fittings.  Most SAE fittings have a groove cut in the nut around the circumference.   Cummins and Detroit used fittings from Stratoflex, now a division of Parker Hannifin and designated as 213 with a DOT compliance.  

A lot has changed since I retired but your classic will likely have 213 hose and fittings with 45 degree.  Many suppliers stock SAE fittings and finding them is not difficult.