I believe there are two versions of the chain drive engines. I have the early version with the single tower and driveshaft underneath. I am with Marty as this one is a real dog. Cracked gears and a motor that overheats in 5 minutes running light. 3 freight cars and the wheels slip.
I am told its the most accurate RS3 though for is prototypical dimensions. All the rest are over width to accommodate the motors. If I keep it, it will just be an ornament next to the engine house.
Pete