Charlie - First, about the grapple. When I talked with the PowerTrac folks, I asked them about a 4-in-1 bucket, but they don't build one. I was going to get a Long 4-in-1 and have them weld the attachment plate on it, which they don't have a problem with at all. They said to just have it shipped to them, and tell them how high from the bottom of the bucket it should be attached and at what angle in relation to the bottom of the bucket. This is important, because it affects the depth of dig and lift height, and the dump & rollback angles, respectively. I was just going to have it welded at the same height and angle as the stock PT bucket.
But, and this is an important 'but', the reason I was going to Long for the 4-in-1 bucket is that a 4-in-1 and a grapple are entirely different animals and excel at entirely different tasks. If you're primarily interested in moving brush, logs, etc., then you may want to go with the grapple, but the 4-in-1 is a lot more versatile bucket, in my opinion. The grapple is pretty much just a regular bucket with a means of holding a load in it - this is over-simplifying it somewhat, but not by much. The 4-in-1, on the other hand, will do everything the grapple will do, though it won't hold as much brush, etc., but it will do all kinds of things a grapple won't. You can pick up loose material with it, grade in many unique and versatile ways, etc. Do a search on the archived info about 4-in-1 buckets, and you'll see what I mean. All I'm saying is, don't pick a grapple bucket because it's all PT builds, and assume it's going to be similar to a 4-in-1 - they're not.
As for the linkage question, it's very complicated to describe, at least for me. Basically, you have two joysticks. The left one acts just like a regular FEL joystick. The right one controls the 4-in-1 bucket, but there's some linkage that connects it to the left joystick. The net effect is that you can open/close, rollback/dump, and lift/lower the bucket
at the same time. (Obviously, I don't mean you can open & close the bucket at the same time, but that you can do one of that pair of functions at the same time you're doing one from any, or both, of the other pairs...) It's a whole lot more complicated to design or explain than it is to use, I can tell you that. As for a place to refer you to for a diagram, I don't have a clue. I also doubt that you could put such a linkage on a machine not designed for one. All the versions I've seen were complicated enough that they were floor mounted and required more space than you would have on a loader-mounted or console mounted version. I'm not saying it couldn't be done, just that I don't know enough about them to see how it could be. I looked a little at trying to figure out how to do it on my Kubota, and decided it wasn't feasible.
MarkC