You're right, it was Arable, but not a Quadtrac, just wheeled case, pulling a 4m set of tines at 4-6" depth, then a set of vaderstdt discs and then a small cambridge roll. Problems were the trash flow through the tines, but generally the machine appeared to work very well.
I have thought of pulling 10' simba 2b behind 2 leg subsoiler as pulling tractor would always be on firm ground to prevent wheel slip. Seeing how much pulling, the discs take when used on their own on land that has been subsoiled has made me realise how strong the link between the discs and the subsoiler would have to be.