Real trucks have two spark plugs. Here's a youtube of my 1958 FWD with the 140GZ Waukesha (F554G in later years.) I have always been kinda partial to Waukys, or "thunder pumpkins" as they were known for their orange color. Many do not know that Wauky is still very much alive and well building mainly LARGE gen set power plants, they were under the name Dresser, however they were recently purchased by G.E. Many Waukys,especially the 145GZ (F817G) were installed in firetrucks, however their track record wasn't exactly the greatest- many tanked after a few years. I found the Waukesha Engine Historical Society online, and spent about an hour on the phone one day with a former engineer. He explained that the mettalurgy in many of those engines was bad, and that the castings down at the bottom of the cylinders where the cyls met the block would go bad, leading to coolant leaking into the crankcase. Mine has a Zenith heated downdraft carb, and as you can see in the video, quite an extensive air cleaner. The video was taken at the Mack Trucks Test Track, and also on Interstate 78 getting on E/B at Lehigh Street heading towards "the wall" of South Mountain just before Route 309. Mack used this stretch of 78 for years to test new stuff.