255371-00 Gasket, water pump cover. Used on the 2300 series Hercules Gas and Diesel engines. Onan there is where the differences

there is where the differences are

no one ever repaints a new motor or pump so that will be your first clue that you may have to pay a little more attention to what's going on in this area of your machine

388001 OEM Oil pressure gauge

Lister Petter used 3 or 4 different belts (in length) depending on how their engines were configured for a particular application

255371-00 Gasket, water pump cover. Used on the 2300 series Hercules Gas and Diesel engines. Onan there is where the differences255371 00 Gasket, water pump cover. Used on the Hercules 2300 series industrial engine. This will be item number 8 in the Hercules drawing.