I went to dealer about 2 weeks ago and them replacements were in the parts depots in stock. not sure what your dealers parts guy is doing, (sounds like nothing) but they need to stay up on the inventory in the depots and push it thru. Sound like they don't have a technician that wants to tackle...
replacements are not "gen3", latest version would be latest updates to "gen2" 14-18 MY service engines now being built. part numbers will change either with last 2 letters or complete part number change. Some MOPAR service engines are now long blocks not completely dressed assembly line ready...