How to fix head block engine cracked

I though my 4 runner v6 blow head gasket. I towed it to repair shop.they found out that
the engine had oil @coolant mix.please tell me What is the problem? how much does it cost to fix it?(Radiator is broken 1 time cause overheat .after I replaced it then 1 month later a lot of smoke came out from the pipe @ smell gas)

So do you know it's not the head gasket? I'm not overly familiar with that engine but that is a symptom of head gasket failure. Oil and coolant passageways in a head are pretty close together and I have seen heads crack and do this as well. If your engine had overheated enough to crack the rad your engine might have gotten hot enough to take out a head gasket or warp a head. This would also give you the smoke and gas smell out of the exhaust because that can lower your compression. I'm thinking the best thing to do would be to pull the heads of and take a look or possibly find someone to do a compression test. You might find one bank with low compression and one with higher which will tell you where to look.