Shower/toilet base is cracked. Can't find a new one

[coach mary]

The floor of my shower toilet combo has cracked and split away at the shower base where it rises to the toilet ledge.    The space dimension is 35 x 23.  I can't find a replacement. Does anyone know who manufactured it originally?  Does anyone have a good solution?

The door opens into the shower basin with the drain at the far left corner.  The toilet sits on a ledge to the right in the center of that section which is 18" of the total 35".