we were driving down the road and we notice that the car wouldnt go in to 3rd gear and when we went quicker it would just rev. then further on down the road there was a load clunk and the car jolted 3 times and we lost drive. we had to put it in to second gear so that we could move out of the junction on to the verge. does this sound like gearbox over heating? btw there was no smoke in the car and no oil left on the road. but there was a strong smell of something burning.