You have a couple options on the subframe as the Grand L40's accept both the old style (duckbill) subframe or the newer 4-pt system found on the Grand L60's.
(Duckbill is what I call it... Not certain what Kubota calls it)
Older subframe found on Grand L30's and 40's (and what I have)
L2180-1 Quick Hitch
L2186 Driveline Kit (
L4240,
L4740,
L5040,
L5240,
L5740 L4330,
L4630,
L5030)
The L2180 can be used on any size Grand L30/40's. It adjusts for length and height to fit all the different models and tire combinations. What is different is the Drivelne kit. When buying used it might be necessary to purchase a different driveshaft due to the length changes between models. They cost about $300. Changing the driveshaft was the only part needed to move the subframe from the
L3130 to
L4740.
The newer subframe released when the L60's came out can also be used, but is very expensive compared to the L2180 subframe.
L4554(A) ) K3 Auto-Hitch
OR
L4455(A) K1 Manual-Hitch
And
L4484 Driveline Kit (4cyl)
Completion Kit is also needed:
L4432 when using on L4554(A) Hitch
OR
L4431 when using on L4455(A) Hitch
Recommended:
L4456 Ground Pressure Relief
As you can see there are a number of items needed for the new style subframe.
Keep in mind a snowblower is needed with the subframe info listed above. Since you're focused on a cab model, the blower will require some way of rotating the chute (typically hydraulic) and some folks like to have the option of adjusting the chute deflector which can be electric or hydraulic.
(I have hydraulic rotation and electric deflection on my blower)
Highly recommend you find a 6' blower as the 5' blower will not clear your tracks. I even added homemade extensions to my blower.
https://www.tractorbynet.com/forums/kubota-owning-operating/390742-snowblower-wings-homemade.html?highlight=weld
Hope the info helps your cause.