What did I buy? A box ? a core? Or did I really buy a tach? https://www.ebay.com/itm/Halftrack-Diamond-T-WHITE-TACHOMETER-NOS/324058987543?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2648 Guess I will find out in a few days....