Make sure you get the correct bulb base for your fixture. I bought some ebay lights that came with 3 interchangeable bases - none of which fit my trailer.
Check the base on your present bulbs and note if they are single or double contact.
There are two types of LED that you can get - panels or corn cob. I think which type you get is up to you. I ordered 2 panels (wrong base) the fist time and then ordered 6 panels with the correct base. I placed 1 panel in each of 6 fixtures since we rarely turn on both lights in a fixture.