They came of a crown forklift
4000lb capacity
I purchased a really nice set of clamp on forks from these folks...
I cut two pieces of 1/2" steel to use as a bucket support when screwing down the locks...
I have had very good success with these and would highly recommend them for those folk looking for a lower cost alternative or those that have a pin on bucket...
Clamp on Loader Bucket Skid Tractor Pallet Fork chain | eBay