i found a 90 240 with a blown headgaset. i dont have a whole lot of money right now so i just wanna get fix it and drive it. how hard is it to replace a headgasket?

 

I do not know how difficult it is, but I can tell you that head gaskets only rarely spontaneously fail. It is very likely that the head and/or block are warped and will have to be milled at a machine shop, if the warping isn't too bad..