There was a Mid PTO option for those tractors. In fact i just added it to my L5240HSTC, but the "C" is the biggest factor in how easy it was. The cabs have the internal gear already installed but the open station ones do not and have to be split to add it first, along with the external PTO gear/shaft. I just pulled off the cover plate after draining the fluid and popped on the PTO gear in place of it. I doubt I would have bothered even thinking about it if I had to split the tractor, but everyone has their own POV on issues like that.
But I seem to recall that you cannot fit a belly mower to the larger Grand L tractors of this -40 series for some reason. If you have or are willing to add a Mid PTO, you should find out the answer to that question first, and I am not sure why.