Is this chassis it's original length from Ford, or is it cut and extended by the Mor-Ryde folks for Jayco?
Probably a stretch. It shows a 181" WB and Ford lists a 158" WB on it's web-site for that chassis. It's easier for JAYCO or any other manufacturer to do that since they don't know what or how many of each floor plan will be ordered in a given year. They order the base and have them stretched according to how the orders come in.