Thinking about getting an LED light to replace the old 4509 in my Cherokee 140. I see that Whelen has one that is STC'd and PMA'd for the plane. It looks like Aircraft Spruce lists a Parmetheus and an Parmetheus Plus for PAR-36 replacement, the "Plus" one being $7 more. Can anyone tell me what the difference is? The Whelen website only shows one PAR-36 14V landing light, no mention of the "Plus" model.