How do you install a tachometer in a gmc truck?

Hi, find the dizzie,trace your harness from the dizzie ,about 3 to 4 inches from the dizzie you"ll find a connector (single white wire) connect this to your taco live lead,having fed the lead thru into the cab where you want to position your new taco,other leads from your tacho are earth(ground) illumination to your dash lights,

think that's it ,have a nice day......Phil LIVERPOOL U.K.