The label next to the driver seat says "Manufactured by Winnebago Industries 8/05". It also tells me that the chassis was manufactured by Ford in 5/05. There is not a day, only month and year. This is the same label that has weights and tire pressures. My info case also has a duplicate of the label. I think this is probably adequate info. If you need the exact date, you should try calling Winne. as John suggested.
2010 Winnebago Journey Express 34Y
2010 Freightliner XCS (mfd 9/'09)
'07 Saturn Vue V6