Another welcome to IRV2...
Concepts were way ahead of their time... And have many loyal, proud, owner's!
Here is some historical posts related to Concept's... (I'll share, that when asked to help another person about 10 or so years ago, to research Concept's. We were nudged to look more for the later era with Detroit Series 60's. That being said. Condition, condition, condition. With documentation, documentation, documentation - would/could be more important then that DD 60's... Only you can determine that!!!).
https://www.countrycoachforums.com/i...rch;sa=results
Happy hunting,
Smitty