I have two 8a models. One is yellow with type B engine (closed at rear only), with yellow driver and black hat. There is no such kind of variation on Nick's guide. There are 3 possibilities.
1- This model is repainted/not genuine
2- This model manufactured in early stages without painting the driver to red (unlikely because trim is silver)
3- Model manufactered and painted at later stages with an older cast.
Here is the discussion about authenticity of model in the other topic.
viewtopic.php?f=11&t=4305&p=46737#p46737
There are some other pictures in the link. Here is a picture showing engine type.

And also the other 8a model fits with code 6 on Nick's guide. But there is a hole/gap behind drivers legs.

Do any other collector have this kind of models?
Regards,
Burak