Review on Enhanced GM D1561D Headlamp Switch - Genuine Parts for Optimal Performance by Mike Woolford

Fits my 1990 Chevy K2500 exactly. Much faster than the original switch. This is a common point of failure on these trucks, as all of the current for the lights goes through the switch. You can fix this by adding a relay to your headlights and connecting the headlight connector wires to the control side of the relay. You can buy ready made "heavy duty headlamp harnesses" that are just that. So the switch only controls the relay, not the headlights themselves. You don't have to replace the switch again and your headlights will work better.