You're going to love the extra power of the MX5800! I certainly did when I traded my
L3430
I ordered a "factory" T&T kit when I bought the MX5800 in May of 2016. The dealer told me Kubota didn't make the parts, they just told the dealer which cylinders to order. The top link worked ok but they had to try 3 different side links before they found one that fit. Even then, I had to modify the installation myself to keep the lift link from shearing off one of the cylinder ports.
Kubota may now offer a kit that fits and maybe you have a dealer that knows what he's doing but if it were me, I'd wait the 20 weeks and have Brian at Fit Rite put a kit together for you. He did a fantastic job on a kit for my old
L3430 which also works nicely on my
L6060.
Be aware that your 2 rear remotes will be used for the T&T kit leaving you no spare ports for other implements. For that, you'll have to use a diverter valve or disconnect one of the T&T cylinders. Doing that will of course partially disable your 3 pt hitch.
I do a lot of grading with a power angle stone rake behind my MX5800. The rake requires 3 remotes, two for the T&T and one for the angle cylinder. I used a diverter valve for a while but eventually added a third rear remote for convenience. Just something to think about.