Hi Luca, i have a tst cart for you.
Tst micro cart from a ~2013 55 micro sta.
Also have the adjuster knobs if you need them
Pm me for more details.
Ps, you can fit SOME 66 parts into a 55 chassis, such as rc3/evo carts, but you need the 55 topcaps, so not really worth the hassle