Moving down (size-wise) from HO to N has been interesting when it comes to adding DCC sound to older models. After wasting a couple of DCC decoders trying to get them inside older split chassis or Life-Like mechanisms I came to the conclusion that a) isolating the motor is easy, the rest is a PITA; b) DCC is not too bad; c) DCC sound is a challenge. There are plenty of PNP sound decoders available, milling the chassis can problematic. In the case of a Life-Like model it means getting rid of the weights, which affects traction.

I model the Great Northern in Empire Builder green/orange or Big Sky blue colors, finding a modern DCC sound-equipped model in either of these color schemes is usually a hen's teeth exercise.  So, I thought I'd try buying an older, pre-DCC or modern DCC-ready model for the shell, and buying a modern DCC sound equipped model for the chassis/decoder/speaker. The latest conversion is an Atlas DCC-ready Great  Northern GP9-TT  in the Big Sky Blue color scheme as the shell donor (roof-top air cylinders and passenger steam-heat boiler equipment), and an Atlas  DCC sound equipped GP9-TT chassis donor (Rock Island colors). I've previously taken this approach with 2 Southern Railway models (E6A and E8A Life-Like shells and BLI DCC sound chassis from their E7A/B or E8A/B models). I have also used the same approach with 2 Great Northern E7As.

I also model the Southern Railway, so that GP-9 TT Rock Island shell is now stripped and waiting to be painted. I'll get a PNP sound decoder for the chassis from the DCC-ready model. Waste not want not. I'm currently looking at 2 Life-Like SD-7 Great Northern models in Empire Builder colors.  DCC is not an issue, sound is. Time to see what's available in DCC-ready or DCC-sound  equipped models as suitable chassis donors.