XOn the cab lights. Check out ddm tuning for some hid bulbs. They are pretty cheap and u will be amazed at the difference. Go with the 4000k temp. I did 6000k and they are a bit too blue. Side and auger go with LEDs or some sort of sealed beam hid.
I use cheap LED's from ebay. The LED's do not replace your factory lighting its more of a supplement to the factory lighting in most cases. I do have some HID's in the cab of my combine that replaced the factory bulbs with some HID's for 45$, but the ballast tends to cause ALOT of radio interference when you turn them on.
Two HID's in the cab in the center lights and LED's on either side of the cab