Electrical: the leading unit has 2 motors controlled by a Digitrax DG583S decoder. The other units are not powered.
The leading unit uses the MTH built-in sound system, but wired through a rectifier. It reads the motor speed from transverse bands on a fly-wheel, but does not produce horn or bell sounds. The rear A unit has a Soundtrax DSX decoder which produces all sounds including horn and bell.

Couplings: Kadee No 821 couplings were fitted.

Wheels: new wheels with scale flanges were turned from mild steel round bar, bored to 8.2 mm to press onto the existing plastic insulating bushes.
The increased back-to-back wheel spacing (42.4 - 42.5 mm) reduced the pressure of the plunger-type electrical collectors on the backs of the wheels. This was compensated for by slipping small brass caps over their ends - increasing the reach and at the same time giving a harder wearing surface.

1.0 mm wide washers were turned from Delrin to go on the axles inside the wheels to reduce the extra sideplay from my increased b-b. The locomotive now runs perfectly through my 1.4 mm wide point flangeways.