Disclaimer: This apparatus is not intended to cut up an entire yard of sod for relaying elsewhere. It's meant to cut a neat'ish strip of your existing lawn to be rolled back, so as to trench for shallow utilities (such as gas/fiber/electrical) going to a secondary structure, or for laying down sprinkler lines neatly.
The kit-and-caboodle slides into a normal set of forks, so as to apply slight downward force and angle to promote rotation of the disks. Speaking of disks, spacing is set 16" apart, in the event the strip of grass cut out is not salvageable and must be replaced with an actual strip of sod. The disk themselves have a standard five-bolt pattern with self-centering nuts. The are constructed out of 3/8" steel plate to prevent collapse. I tested it this evening, lifting the front end of the tractor on just the disk: still measures perfectly square afterwards.
Around me a sod-cutter rents for about $180-$200 a day (About $120-130 USD), and they are rare as a hen's teeth. This whole device, including axle stubs, steel and fabricated disks (the biggest expense), set me back about $650 CAD (about $400USD).
Again, this is not a substitute for a proper sod cutter. It is simply a "cleaner" way to trench to avoid costly repairs during restoration (or a long wait for grass seed to fill back in the bare soil).
I wish my welder would have had the time to finish this before winter and frost set in, but he was swamped at his job, and his work is fantastic, much better than I could ever dream at welding. He finally got a chance at it during his personal Christmas holidays, I'm very grateful he didn't abandon the project.