I'll try and answer all 3 of your questions in one post. Your diff, will be fine if it's a 165 that is the bigger one fitted to the later bigger engined utes. If it's the 145 1200 diff you may find reliability suffers. Most people have moved on to a stronger diff than run a diff that is marginal as best. You can have the axles & carrier shot peened to remove stress in the parts. On the GX manifold issue they are increasingly rare and I wouldn't be using one on a competition car. If you want extractors they are still available in OZ and if you have problems they are easy to source here in NZ. The same with 5 speeds, if you get really stuck I can sell you one I have at least 5 at the moment,I grab any that come up for sale. Wayne...