Originally Posted by Diseasel300

Diesel cars require the diesel tachometer head, there is no substitute or workaround. The gas cars use the ignition pulse from the ignition module for tach readout, the diesel count flywheel teeth. Additionally, the tach pulse for the 603 engines comes from the EDS computer. If that wasn't transferred to your swap, you do not and never will have a usable tach pulse unless you get some sort of aftermarket tach setup.