Thanks for your replies. I guess the photos posted by Andy are of an earlier version than mine, which I wasn't aware of, because they are numbered 8002 whereas mine are numbered 8025.
The difference being that the 8025 versions without the exhaust stack and the black stub don't have the word LANZ on the radiator front, and the boxes are different.
What model number is the original green version shown without the exhaust stack ?
I assume that the models in the photos are all in diecast metal, which still doesn't answer the fundamental question, however, as to whether there was a version made either in plastic or resin, in green with a black exhaust stack.
Nice to see the red version with yellow wheels, which I have never seen.