For anything that uses Lionel RailSounds and has a battery connection, I would naturally recommend the YLB. These are designed to work with any version of Lionel Railsounds from RS 2.5 to the latest Lionel Legacy RS-Lite boards. One wire connects to the center track power and the unit is installed. Note the circled connections in the graphics below for the two types of battery provisions.
There are two versions, one for older RailSounds that has a battery cable and clip.
One is for new locomotives that use the RailSounds-Lite board, many recent versions don't include the battery cable. This version plugs directly into the RS-Lite battery connector.