Replace/repair grey holding tank

[fonsecaangelm]

Hi there! We have a leak in our grey holding tank, and already patched it with ABS, but either it didn't work, or we didn't find/patch all the cracks. So....we will be opening the bottom back up and checking again, but, we are thinking we might want to replace it.

Does anyone have any tips on
1) where to find the replacement part # (is there a registry of part numbers for our year/model?)
2) once I find the part, has anyone found an owner's schematic of how components are mounted?
3) what to watch our for? who's done this???

Thanks for any information