The crack being in the middle above the slideout is nowhere as serious as being on either end of the slideout opening. Being in the middle says the beam has flexed, most likely from the weight of the roof and the cabinets inside and what was carried in them. Bouncing down the road or just a constant down force that caused the beam to sag a little over the 10 years. All that should be needed then is to properly seal the crack outside so water doesn't go in. With the crack being where you now have told us, that makes a huge difference and I would not be afraid to purchase the RV if you find no softness or visible water leak streaks inside along the slideout upper support beam area. The $15,500 price in the overall condition you stated is a good price. Thanks for clarifing it.
