LED's keep advancing, I did the LED upgrade about 4 to 5 years ago. They had less light output and cost more but still a worth while upgrade if you are doing dry camping running off of batteries.
Here is were I bought mine from. I linked this page as it has the socket type I believe you are looking for
I see now Amazon has lots of them too. Others have bought from many other places too.
When I was looking for them, the auto parts stores only had LED's that worked in the Auto's, more of an end of bulb type of light(like a brake light) not so much the RV type of application that needs light all around (like a ceiling light) . That may have changed or not.
Here are a few quick tips.
Make sure the ones you pic has at least 100 lumens of light output. More is better but less and you may not be happy. Getting way over 250 lumens and above might be getting too carried away and you need sun glasses inside. You can see the difference between 100 to 120 and or 150 and that is a nice upgrade in light with 100 sort of being the bottom end number. I have several 105 lumen bulbs as they did not offer much more back then. Now 120 to 150 can be found, lower price. We only have 1, 200 lumen bulb for wife's reading area and it is in a glass fixture to shine out the end on purpose.
Cool white or warm white light output?
Cool white is better for reading in many cases but some do not like it for general use as it is too, "bright".
Warm white is closer to the older incandescent bulbs glow.
In our case we have mostly warm white but wife has a cool white by the bed and the couch where she does a lot of book reading.
Hope this helps
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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