I haven't heard it called a "reluctor wheel", but there is a timing ring attached to the flex plate on later 240s and 740s. There is an RPM sensor that picks up signals from the timing ring as it turns. It is mounted on the top side, in a notch in the bell housing. The clearances between the RPM sensor and the timing ring need to be consistent. The timing ring in the picture below was damaged, and the car did not run. Straightening the timing ring while in place got the engine to run, but not well. The fix was to drop the transmission and replace the flex plate.