Can someone tell me the correct VIN configuaration for a 1986 3dr Sierra Cosworth....

I am going to check a chassis number with Ford tomorrow (on a car I viewed today), however I am slightly concerned that the model type on the V5 does not say Cosworth, and I want to a) make sure its a genuine Cosworth and b) get together some ammunition for getting the DVLA to change it.

Thanks Paul