thank you Philippe!
I don't remember about the hole, this evening i'll look.
Looking at pictures from Lego, they also differ in the joint between the plate and the engine:
http://cache.lego.com/media/bricks/5/2/347526.jpg
http://cache.lego.com/media/bricks/5/2/4660876.jpg
old version was thinner, with a step beside the plate, while the new one is thicker and more continuous
I don't remember about the hole, this evening i'll look.
Looking at pictures from Lego, they also differ in the joint between the plate and the engine:
http://cache.lego.com/media/bricks/5/2/347526.jpg
http://cache.lego.com/media/bricks/5/2/4660876.jpg
old version was thinner, with a step beside the plate, while the new one is thicker and more continuous