Can someone tell me if all in line 258 6 cylinder 4.2 engines are the same. My 258 blew a head gasket and wound up with a cracked head. I've got a chance to buy a newer 258 with 89.000 miles for $200. I just want to make sure it will fit in my 1980 CJ7. I believe the newer 258 is a 87 year. Any advice will be greatly appreciated.