when you change the final drive ratio. If I understand correctly, you are talking about changing the transmission only. That won't affect the final drive ratio (dictated by the differential ring and pinion ratio). The only ratios that could change, would be that of the transmission gears. If you are looking into changing the diff gearing (from the NA 4.08 to the TT 3.69) you need to find an R200 differential compatable with a swap into a Z32. Hope that makes sense. Mark