I agree with Powerscol. My Kubota has slots in the sheetmetal for 3 rear remotes. I really only NEED 2 - one each for top and tilt, but hey, while I'm doing it, an additional stacking valve is only about $250. Specifically, for mine, the Kubota OEM price for a single non-float/detent valve is $233. The same valve with float/detent is $293.
Which brings us to another question you need to decide - do you want to have float/detent or not? Float/detent just means that the hydraulic cylinder attached to that particular valve doesn't get hydraulic pressure either way (extend or retract). So it is free to extend or retract based on whatever forces are applied. I figure that this will be particularly useful for the "top" cylinder for a bushhog to allow it to follow ground contours as needed. For the other 2, I wasn't sure, but for just $60 additional, I got all three with detent.