"Long block is an automotive term for an engine sub-assembly that consists of the assembled block, crankshaft, cylinder head, camshaft (usually), and valve train A long block does not include fuel system, electrical, intake, and exhaust components.
they installed a new motor minus what is mentioned here. If the coach is priced fairly i would consider it. Sometimes engines fail. My 1986 K-5 blazer blew two pistons with 15k miles on it, it was a trade in that i purchased, GM installed a new short block and when i sold it it had 275k on that engine.