Excellent deal here. As for the cab, Sega was known for using whatever was on hand for the US cabs. You can and will see many combinations of plastics/colors used is the Model 3 racing cabs. Many of the ECAs came in these yellow cabs, however, most had the yellow seat-backs as well.
It is also noteworthy that Sega released ECA as an upgrade, so this could be a conversion. I do not think this is so, simply because the seat-backs for D2 were of different styles, but always yellow. I'd say this is an ECA from the factory.
Regardless... SOMEONE BUY THIS THING!