i was heating, with a hand held torch, the block, at the one side drain plug for water jacket on the 350, to get the plug out. well, where that is, the block comes out a little, right at the threads. a chip of cast came off. about a1/2 inch long, maybe like a 1/4 in. deep. you think i`m in trouble with a crack like that, plenty of thread left. i thought since the piece that came off, actually circled the threads, i would`nt have a problem.