Hi , this is a great well did mod , but i think theres an issue with the tracks on the big steiger ( 715/785) when the tractor is pulled by another force on the back the tracks tilt in the air and when moving forward without nothing pulling the tractor on the back the tracks slowly resets back to place . I dont know how to really describe it so i send you a photo 
, if you can help me with this it would be great thanks , thanks again for making a good quadtrac model