Couldn't tell you the year of the switch, but the earlier units had a Queen bed slide, with the window in the back wall, and cabinet down the curb side. You would sleep laterally with your head at the side wall. Later switched to a King bed slide with windows in the slide side wall, and cabinet at the head of the bed. You would sleep with your head at the back wall. But pretty good chance the slide size change was in 2011 when the stronger motor went in.
2011 Jayco X19H (purchased 2015)
2008 Jayco 1007 PUP (purchased new, traded for the X19)
2012 Chev Traverse LT with TP