As I was saying in another post I replaced all of the original incandescent bulbs in the taillights on my friend’s MY88 car with LED bulbs. I did this at the same time that I replaced the lenses on the outside of the lamp housing with two NOS lenses he bought off of Welsh Enterprises. His were cracked so he was lucky to get these other lenses from Welsh. After I had cut the old lenses off the taillight housing I got to looking at what I call the light defuser plates that sit behind the outer lens. These light defuser plates convert the white light from the original incandescent bulbs to the red or white as needed. So there are three red light defuser plates and one smoked white defuser plates behind the outer lens. So since I was planning on the red or white LED bulbs I decided to do away with these light defuser plates when I glued the outer lenses back onto the lamp housings.
The resulting lights from the taillights are noticeably brighter than the light from the original bulbs that has to pass through these thick light defuser plates and the LED bulbs seem to put out much more illumination than the original incandescent bulbs. Also I believe the LED bulbs use less power to run them and produce less heat.
In case anyone is curious, the bulbs I used were obtained from ebay listings shown below.
And, knowing W.E. (as I do now), I’m sure they didn’t mention that using these LED bulbs on exterior lights in your XJ40 will trigger your “bulb out” warning light to not extinguish, due to the differences in electrical resistance. It is my understanding there is some aftermarket gizmo one can buy that corrects for the difference in resistance to prevent the light issue, but don’t know if they have one specifically for Jags or XJ40s in particular, if so.