

I have Ken's Bolt On Grab Hooks on my bucket. Great product.
Ken only offers 5/16" Grab Hooks because 5/16" hooks are a sort of universal size.
5/16" Grab Hooks will hold 3/16" (sort of),
1/4", 5/16" and
3/8" chain securely.
5/16" Grade 43 chain is likely what you want.
With a compact tractor you will lose wheel traction before you can stress 5/16" chain.
3/8" chain gets awfully heavy working with it during a hot afternoon.
Both Lowe's and Home Depot offer a box with two lengths of 5/16" Grade 70 chain with 5/16" Grade 70 Grab Hooks attached to both ends at a very good price.
(Grade 70 chain = Transport chain)
Even adding in the cost of two clevis Slip Hooks to replace two of the Grab Hooks these kits are a bargain.
If you will use your bucket to "roll" saplings out of the ground, roots and all, you will want 6' of 1/4" chain with a 1/4" clevis Slip Hook on one end. The 1/4" chain links will grip 1" - 2" trunks where larger chain links will slip.
I once damaged 5/16" chain when I towed a huge (1000 pounds) pile of brush about 3/4 mile over a rough, paved road to a burn pile; several links under the pile were considerably abraded by the road surface. Cut out damaged links with a Sawzall and rejoined the two undamaged pieces with a clevis connector. After this experience I make smaller piles and move them with Payne's debris forks with the bucket raised. Often cannot see forward through the load, so drive in reverse.