When I bought my Woods 750 Backhoe, it was mounted on a JD 770. The previous owner had used it for trenching septic tanks, leach beds, and footers as a full time business. He didn't have a sub frame kit on the hoe, but did some beefing up on the 3 pt hitch (stabilizers). I use the same hoe on my JD 4500, according to JD info, the hoe is the next size smaller than what is recommended for the tractor.
Good Luck.