Charlie, I believe all interior bulbs are the same when it comes to the bulb's base (aka, a 194 bulb will fit into all interior sockets of the Riv, as will 161 and 168 iirc) but they do differ in number. The number is different because different numbers indicate different wattage levels and levels of brightness (194 is highest iirc). I replaced all interior LEDs around 2 years ago with ones from Super Bright LEDs online and all of them still work like new. Check this page out. Mine are the ones at the very top of the product list: http://www.superbrightleds.com/cat/miniature-wedge-base/filter/Cross_Reference_Number,WLED,21,201: