I put this in here since it is specific to the 2013 Ram. I had previously started toying with the interior lights but when I realized there was a different configuration for this year, I backed off and asked.
I had posted a question about replacing the LED's in the exterior and interior lighting section of the forum and had not received a reply (that worked) after bumping it a couple times.
Unfortunately, the book for the 2013 Rams has not been updated with current information. It's a nice day so I decided to have another look. Here is what I found. You may not like it.
The front map light bulbs are pretty strange looking and they are behind chrome painted plastic pieces. To get the bulb out you have to remove the chrome pieces and by the looks of it, there is no way to get them back on.
This pic is a new light on the left and the chrome plastic piece still affixed on the right.
Lights on: new on left, old on right.
Chrome housing (top) and old bulb (bottom).
Lights off (sorry about the reflection, sunny day and I'm not complaining).
The light in the back seat of the truck is affixed to an approximately 2"x4" circuit board. There is a bulb that is part of the board. There is no changing this bulb without changing the board. I tried to take a picture of it but it is a very tight space and I did not feel like further disassembling it since I cannot swap it out.
So for now, I will have blues in front with no chrome piece in front of the bulb. Still have white light in the back. The rear lights in the Challenger aren't user configurable either, similar to the LEDs near your feet in the back of the Ram. We have blue in front and white in rear in that car too and it still looks great.
The bulbs that I had, which thankfully worked are part number 921-B9 (wedge base, 9 LED bulb) from superbrightleds.com. There is no issue with them not turning off when they are supposed to so no resistor should be needed.
Hope this helps.