Here is the issue.... a buddy of mine has a 1990 240 SX with and SOHC. He picked up a cap and rotor for a 1990 240. The rotor would not fit. He took it back and asked for one from a pickup and it fit. So now he thinks that he may have a truck engine. He bought the car used and is not sure of the history of the car. He had his head gasket replaced and at the same time had a new timing chain kit installed. Now there is a bunch of racket coming from the timing chain area. He did not tell the mechanic that he thinks he has a truck engine. Now he wonders if there may be a difference between the truck engine and the 240 engine. The noise was not there before having the new timing chain kit installed. You rev it up to about 2,000 RPMs and it sounds like the chain is slapping around. The mechanic told him that the piston pin is probably worn and the piston is slapping around. What do you guys think? He paid the guy $1,000 for the repair and the car sounds like crap. My friend is not into motor swaps......he is 48 years old.