It's my understanding that the F707A takes 2 different spark plugs (one type for each side). When I got the truck it had Champion D23 plugs running both sides. Is this acceptable? What are the proper plugs to use on each side? Also, there seems to be a great debate about oil and old engines. Not knowing the history of my engine, i.e. rebuild, or type of oil used previously, etc. , should I use non-detergent oil just to be safe? If a detergent oil HAS been used, will using a non-det oil subsequently cause any harm? ? Where do I find a high quality 15W40 non-det oil? Last question......... the air cleaner is mounted drivers side back by fire wall. It's cannister with an intake port about 3 1/2" diam. Should this port be wide open like this, or is there supposed to be a screen, or tube connected to it?