I have done it in a 248RBs. Easy install. Dometic 310 with china bowl, high model. My wife hated the thetford and the flush by hand. Grandson would use it and pee would be everywhere. I sold it for 75.00 anf bought the Dometic for 162.00
] Wife is happy so all is okay now.
Only proble I had was making the plumbing fit. I had to cut the main line. and install a new pex fitting, but I had the tools for this. Jayco plumbs to fit, the thetford line was at the handle, dometic is on the floor.
check ebay colaw is also there and offers free shipping