Given that there is sufficient space, the soundcard can be installed within steam locomotives or their tenders. In both cases, it may be necessary to remove some or all of the lead or steel weights. In that case, the traction of the locomotive is unlikely to be affected because a heavy battery is to be inserted in the place of those weights.
Small tank engines will probably not have sufficient space and a sound trailer should be used instead.
The photo shows an installation in the tender of a Hornby Castle loco. When the soundcard is in the tender, then the input from the track could be achieved by phosphor bronze wipers picking up from the tender wheels or by a pair of wires running through to the locomotive motor.
