I installed the JD hydraulic diverter on my 3320 open station. I don't think you will be able to do it without pulling the fender which, at least on my open station tractor is the least of your worries, not sure the difficulty on the cab tractor. On mine you have to remove the four steel lines that go from the joystick to the two loader scvs and install 12 new steel lines. four from the joystick to the block that changes flow. Then four to the front loader scvs and four lines to the rear which were a little challenging to add with my existing 3rd scv. The clearance between the lines on the diverter block is extremely tight. I am a master automotive tech with tools for nearly anything and I had to install the lines in a sequence so there was enough room to get any kind of wrench, flare, 45 degree, 90 degree, crowfoot.
I ended up buying a set of these after the fact.
315AN, Set, Wrench, Crowfoot Flare Nut, 12-Point (15 pcs.) (1 1/8" to 2")
A couple of hints.
make sure to clean the lines before you install them. My kit was shipped in the foam peanuts and some of the caps were off the ends of the lines so some had chunks of foam in them.
Make sure your work area is super clean.
Buy some low vis. fluid. you will need to add some
I also relocated the toggle to the fender, instructions wanted it next to my 3rd scv lever. I had to extend the harness and route it through the ROPS into the fender. Not a big deal to soldier on new wire and terminals. Not sure about the cab kit.
I also installed a Power Beyond kit which wasn't nearly as challenging as the diverter.
Hope that helps, Once done, install the top and tilt, hook up the box blade and have fun. Power center link is priceless.......