Generally all challengers sit level even just before they stall. The old 75e used to lift its nose on a 13 leg shakerator a bit but the newer ones generally not. If any twin track hits hard spots and loose momentum they either start snaking in an ‘S’ pattern loosing all grip or you break a drawbar pin and occasionally they pull the cultivator drawbar off. They grip very well. Look for ‘challenger and scraper box’ videos on you tube. If they can collect 50 tonnes of soil without lifting their nose nothing in agriculture will make them do it either. I think the 75e only did it because the shakerator was linkage mounted and that in combination with the flat track design didn’t really work. The newer track design got over that.Did you find the 765D sat level when pulling hard?