I am just starting the rebuild of my 4d55 for my 91 ranger. I took some pictures of the tear down but I don't know how to post the pics up. It was really tired and low low on compression. I think I may just bore it out but I have to look at my options. I have a connection in AU to get all the parts I need. I am going to be building with more power hopefully 120ish hp. I am going to coat the pistons and build my own exhaust manifold, bigger turbo, extrude hone the injectors and build my own intake. It is also going to be intercooled. I will try to do the step by step thing for those that are interested. I know there is not that much info on these things.