I'm looking to rip out the old crusted dash in my truck, and replace it with the style I enjoy, only problem being is the speedometer for new dash is electrical and my current one is mechanical, how would I go about getting this to work? Is there mechanical sending units that go into the cable gear slot and convert it to a pulse so that speedometer can read it and if so how would I go about getting the one I need? I'm stumped and any help would be appreciated