Bernie, they may be installing a smaller tank so that other holding tanks (grey, black and maybe fresh water) can be installed. You might want to look under the coach to be sure someone has not dented in the bottom of the fuel tank, reducing the total capacity. Let us know what you find.
Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7