Does anybody know of any model rail companies that produce a HO scale Russian Rocket-carrier train as used for Soyuz launches, i.e:
The van would appear to be a generator car, probably used to power hydraulic handling equipment.
Similar generator cars were used with some block trains of refrigerator cars.
You might be able to find a model made years ago by Piko when they were still an East German operation.
A possible option might be a Bachmann Chinese 22 series mail van or power car.
The locomotives are derivatives of the Russian TEM-2 type. If you can't find any of those, they were all based on the Alco RS-1 type modified with six motor bogies called type TE-1 (or Da for the WWII originals) which might be modified from available US models. All of these prototype locomotives used versions of the Alco 539 engine.
There is one standard flat car used as a spacer.
You might kitbash the carrier wagon from available models of transformer carrier wagon or steel torpedo wagon.
But this assumes that you might find a Soyuz of the right size.
There was a thread on the Trains.com site on the "Classic Toy Trains" magazine sub-site on downloadable paper models of space vehicles which could presumably be photo enlarged or reduced to suit. The thread was page 4 of "In a standard gauge mood" by "Penny Trains" where direct links to websites were provided by the original poster "Penny Trains". I think a Soyuz was illustrated.