I know this is an old post but letting everyone know that the Model 7 Backhoe tooth is still available from the manufacture, H&L Tooth Company.
The '0' series OSP tooth, JD part#PT8163, can be found much cheaper on the companies eBay store here: H&L SP Original Series Fabricated Bucket Tooth...
There's a 104,000 miles on the original odometer. Ordered and bought it in June of 1984 at the age of 24 and beat the living crap out of it 4 wheeling and hunting to the point of the body tub rusting out and I fell through the floor in 1996. I restored it myself between 2007 and 2011 and...
Recently bought a used 1989 JD 770 with 475hrs on the clock. My 2013 F150 pulls it nicely with a 16ft dovetail trailer I have from Rampant Trailers in NC. Use the trailer often pulling large supplies and my Classic tagged 1984 Jeep CJ-7 I've owned since new.