1996 Ford F350 Owner's Manual - Page 80

Tachometer (If equipped) The tachometer will show you the engine's speed measured in revolutions per minute (RPM). The tachometer may move slightly when the key is placed in the ACC or ON position, with the engine off. This is normal and does not affect the performance of the tachometer when the engine is running. Some vehicles are equipped with an engine speed (RPM) limiting device contained within the Powertrain Control Module (PCM). The purpose of this device is to maintain peak engine speed (RPM) below a specified limit. This feature is only evident on automatic transmission vehicles when shifting manually (1, 2, D) and on all manual transmission units. (Engine speed limits may vary based on engine displacement). If you are experiencing an "engine cut-out" condition at high speeds, it may be the result of this limiting device. It is a normal condition and can be avoided by reducing vehicle/engine speed. Tachometer 78