Original Message ------------------------------------------------------------ ' 183.558 Hoses and connections. (a) Each hose used between the fuel pump and the carburetor must be USCG Type A1 hose. This section and a subsequent section only refer to gasoline installations. I wonder if there is a different section for diesel? ---------------------------------------------------------------------------- --------------- Bottom Line reading the standard and regulations can be confusing. Not to mention in our litigious society a simple brochure or sales sheet is not going to give you  the rest of the story May I suggest following;use the mfgrs. specification sheets when in doubt to be sure, they are usually ready to answer any technical questions also. I do not always trust the wrench to supply me with the most update info and products for my vessel. Here is the mfgrs sheet on AeroQuip FC234 hose as you will see lots of info (note the pages in the pdf file are off) FC234 is page15 If you look carefully on the hose fittings you will see the size stamped on the fittings http://hydraulics.eaton.com/products/pdfs/fc/A-HOOV-MC001-E_04_Hose_11-38.pd f this should be what you want to know and more, enjoy the info Regards Denny Calmeyn F32 Trojan Lake Michigan