I have a GC2400, and I use a Yanmar RSC1600 tiller, ~66". It is missing ~1/5th of its tines, and my garden is sandy. Ray66 is correct about lifting height for trailer loading, but if yours is like mine, the tines just roll when they touch a high spot/lip of the trailer. You will need a front weight to counterbalance a tiller of that size.
So, not knowing your own circumstances, the tiller is of possible use. I would not use it to break new clay/stony ground.