Well my th350 is finally slipping like crazy and I have decided to be on of the adventurous ones to dive into my first tranny rebuild towards the end of January. I am going to be rebuilding a th400 but need some questions answered. 1. Do I want a short or long tail 400? 2. Should I go ahead and replace the flexplate as well? 3. Other than a rebuild kit (Northern Auto Parts #K3400D-R) and the corresponding shift kit and tech manual, new converter, and speedo gear. What else might I need? 4. Is the length different from the 350 to 400, will I need to have my drive shaft shortened? 5. Will the 350 shift linkage work, or do I need to find a 400 linkage? 6. I understand I will probably have to move the trans crossmember, but the holes should already be drilled right? I know it is a lot of questions but I want to be prepaired for this little adventure. Thanks!