LEGO Trains 12v: Identify This?
The red car that you mentioned is Mail Van (7820).



There are a number of other trains in the picture including:

7730 - Goods train (the locomotive doesn't seem to be visible)



7710 - Push-Along Passenger Steam Train (just the cars)



7750 - Steam Engine with Tender (pulling the cars from 7710)



7814 - Crane Wagon



7760 - Diesel Shunter Locomotive



7720 - Diesel Freight Train Set (the car in the bottom right carrying rails to the work crew)



It's not a train, but set 6647 - Highway Repair is also present.