Butch,
If you are looking for the Whelen LED landing lights, here is a link to the best price I have found yet.
https://www.2aps.com/products/led-landing-lights/The ones you want are:
PAR-36 LED Landing Light, 12v
PNO: 01-0771424-10
These are FAA-PMA approved and drop in to the existing mount and connect to the existing ring terminals. They are polarized so if at first they do not work, check to make sure the +/- are connected correctly. Also, the mounting tabs may need to be tweaked in or out for security of the bulb, and many times a layer of electrical tape or some very thin wheather stripping will help the bulb not shake in the mount. It has been my experience that although these ate PAR-36 standard size, the thickness at the housing edge varies some from the incandecent 4509 and "Q"4509 bulbs.
-Zach