I don't have a spare sump to give/loan to you, but worst case is go to Home Depot/lowes and get a plastic container till you get one you need, if this is an emergency. I think Home Depot (Wolfchase Mall area) had some larger ones on clearance for $5. Then you can take your time to get the replacement that you want.
I have a 25 gallon or so that I mix my salt in and used it when I had Barrett put in another divider in my sump.