I'm purchasing 2 units, EMD GP40 and EMD FT-A. Can sound be added to these, where can I find what will be compatible?
Bachmann does not make either EMD GP40s or EMD FT-As in large scale.
Probably better to ask your question on the Bachmann board specific to the scale of your locomotives (ie; H0, N, etc.) or if they are not Bachmann, ask on the appropriate manufacturer's website / forum.
Happy RRing,
Jerry