[Vwdiesel] Resonant Reed Tachometer

[SLATERSFB at aol.com]

You'all probably know of these already; news to me. Picked one up on Ebay for $10.US. Very expensive when new. 
Just lay on dash - no connection - works by vibration. While cruising, lay it against shifter. Checked accuracy with digital tach & seems very close.
Installation of gas tach into diesel car seems complex for the electronically challenged (that would be me). Any one ever do this?