As to owners manuals, I believe most know that you rarely ever get one when you buy a used vehicle. I only have once in all the years I've been driving, and that was with my Lightning, which I bought from the original owner and it was pampered. Other than that, owner's manual with a used vehicle? Don't make me laugh! Most people likely never read them and toss them in the round open top file quickly to make more room in the glove compartment for other not necessary junk.
I've got a 4.0 in a 2007 Mustang. Only problem I've had with it so far is the STUPID plastic thermostat housing. Constantly battling little teeny leaks from the damn thing. And the heater hose pipe that stands up vertical, being plastic, can't tighten it enough to prevent leaks there. I had to put a metal insert inside the thing to stop leaks from that source. Does anyone make a metal replacement for this POS part?