Peggy - I'm in need of a new porta-pottie. I have a Sealand Sanipottie 964 MSD - it developed a crack on the corner where the holding tank has an indentation for the mounting bracket. I found this out the unpleasant way - it leaked. Yuck. I tried to patch it but I'm pretty sure it's still leaking and I won't be able fully repair it. So far I'm looking at couple models. Do you have experience and/or recommendations on these or other units? I don't think getting a new holding tank is practical. One is basically the same Sealand unit. A draw b/c of the same bracket pattern, and relatively low cost. However, I'm worried it will crack like the one I have now and i'm not crazy about the bowl-to-tank seal (drips, smell). I've read some reviews of this happening to other people too, with the bracket design not helping. The others are the Thetford 735/775 (same thing, different capacity) and the Thetford Aquamate 875. These models all cost more than the Sealand units, but look to be studier with more user-friendly features. I'm looking at the MSD versions to have the pump-out option. Do you have any input on durabilty, how easy these units are to operate, empty, and latch in place? Thanks,Brad