Okay i cracked both heads on a 4.0.Okay iwent ahead bought another 4.0 1993 with half the miles from eastcoast. Im from the west coast. for 500bucks s/h included. Great deal i thought. well the engine arrived I had to vlean it up but didnt take the heads off or the mainfold. Put everything back on except i used my manifold axhoust heads instead of the one that came from the east cost. i had a mechanic start it. He said it needed some cleaning out still. so he used tranny fuild okay fine. changed oil again 4 times that night. knocking noise occured because the oil compression drop and had to drive it 2 miles more. Okjay i than drop the pan to clean oput the bottom side. did work. well, being me. i ahd to drive for a week about 40miles more another noise came up so i stoped driving. i pulled the engine after having more money to fix it. 2 off the rod bearing seemed bad 2 and 5. they had alot of play. so instead of re[placing the bearing i went ahead and put the 2 heads on the other engine that i cracked the heads on.everything seemed fine. started it and a bad knocking noise started up. bang backfire out of ther egrthen a blanket ofwhite smoke as soon as the engine started to warm up water in the oil. okay maybe i put the gaskets on wrong or the heads were wrap or something. I found out what the knocking noise was. The piston broke and the rod arm chewed up the cylinderwall. The head looks like it got beat up pretty bad inside the compresion area. The valves seal didnt break or the valves didnt get hurt. The cyinderhead didnt get cracked.I had a mechanic friend look at the heads.What he did was grind down the area that got chewed up. basically took out the dabree that was left. He said that the compression might get hurt alittle but not much.is it possible that the heads are gone or can i use the same head on the engine that i took off originally? a fix the bearings. Or isthat engine screwed up too.the cranks seem fine the bearing that wqas bad was toasted and the journals seemed fine with a few nicks notr bad looks like wear and tear. and the other cranks on the bad engine now seems to bee greatr . is it possible that i should buy nother engine cause im not going to give up yet? Help, what can i do.