Hi Paul, Welcome to the site.
I've been looking for a used one for my 2615 for several years. They are very hard to come by and I doubt I'll ever find one unless someone trades one in on a tractor and the dealer is willing to sell it separately.
You can use any 3 pt. hitch BH but it should be attached to a subframe so it doesn't stress the tractor. I've seen some new ones on Ebay complete with PTO pump for about 4K. I'll probably get one of those and build my own subframe. At this time I have other items more important than buying a BH. Plus I've really only needed a BH 5 times in the past 7 years and was able to borrow one. I don't like to do that in case something breaks. I'd fix it if it did, just don't like to borrow someone elses.
The ones I see on Ebay are made by Taylor Way model 766, Woods BH6000, and Mateng BH6600. All are around 4K price.
One member here has the Woods on his 2615 but isn't using a subframe. Several have the factory BH, and some the Taylor Way.
From the pics, the Woods and Taylor Way BH's look to be well built. I've PMed owners of both and they are pleased with there use.