Dave,
I have not been able to find that exact model name and number, but it likely is similar to this 19RD (rear dinette...)
https://www.gulfstreamrvsource.com/s...n-19rd-tr49829
If so, the tanks are 51 gallons fresh water, and 37 gallons each for gray and black water. Maybe your model is exclusively made for Camping World, since it does not appear on the Gulf Stream website...
Chuck