Received some of my engine instruments today. As per William Wynne's recommendation, I purchased the Stewart Warner diesel tach, which uses a hall effect sensor on the ring gear for accurate readings. Also, the range of this instrument only goes to 3500RPM, which will give me nice resolution. Staying with the Stewart Warner Deluxe line, I also purchased my volt meter, oil pressure (5-80psi) and oil temp (100-280*F - not shown).