200 is only avaliable in 4x4/Escos models, it is a stronger block than the 205. Part of the reason it was used due to the transmission stress of the 4x4 models.

I'm sure there is no such thing as a 197, the number merely denotes the capacity i.e the 20, the 5 denotes 1985 which is the year when the block was revised, the 0 in 200 means 1990 and so on.

The 202 block was indeed a Transit block but it isn't as strong as a 200.

Before such times the block was simply a 20 or T88 block.

In the same way you can have a 165 block but obviously a 1600 Pinto.

Martin