Welcome aboard 3griffs!
We have an '03 Friendship and are quite satisfied with it. That said, I am not aware of any specific thing you need check, but there are plenty of things to consider. I'm not sure what RV experience you have, so forgive me if I assume this is your first purchase.
In general, it's a dual purchase. You are buying a house and a vehicle, so you need to check all the things you would for either, if purchased separately.
For the vehicle: tires-brakes-handling-driveability-rust-dents-etc.
For the house: furnace-A/C-roof-windows-basement-plumbing-appliances-electrical-floors and walls-slide outs-etc.
Last week another new member started a discussion about checking on a pre-owned coach and there were some very helpful responses.
Check "Week Old Newbie"
on this forum at this link viewtopic.php?t=2101
You will find some very useful suggestions for things to check on any
coach. Also, I'm sure someone out there has the same model year 8411 as you are considering and may be able to provide specific info.
Good luck and keep us posted.