I installed a tachometer in the '47 this past summer. It's probably one of the more useful gauges in the truck. The tach coupled with the engine noise give me peace of mind on the road in all driving situations. The '47 has a 1955 235, SM420 w/open drive shaft, 3.90 differential, and 30 inch diameter tires. It will cruise at 60 mph all day long and straight as an arrow.
