I was wondering if anyone knew anything about putting a 4.0 Head on a 4.2 Block. Is it possible? If so what do I need? The reason I'm asking is my old 4.2 head off my 1987 Jeep Wrangler has cracked and can not be fixed. The last 2 heads I've order have been for a 4.0. I guess no one knows that theres a diffence between a 4.0 and a 4.2 I already know that the valve cover will need to be changed but I'm not sure the head will actually line up with the mounting holes on the head. Any help will be appreciated. Thanks.