This type of tow-behind box blade/scraper requires a draw bar.
First spread your lower 3 PT arms and measure how far apart they are - this can vary slightly depending on how the turnbuckles are adjusted. Your draw bar must be equal to or less than the max width.
Second measure the holes where the scraper will connect to the draw bar. Get a bar with the same hole spacing if possible otherwise you'll need to drill to fit. If you use only one hole the scraper can sway back and forth which is usually not optimal.
You can get a 3 PT. draw bar like this (minus the ball) - would be my first choice since you can use it for other tasks. Just make sure the height from the bottom to the top link pin is not too tall to connect your top link.
Or a 2 PT draw bar like this - the simplest and cheapest alternative. Again, measure the width of your lower links and buy a Cat 1 to match.
