Hi guys I need some help with gearbox and diff ratio. I have a 2002 Falcon AUII XL ute and I replaced the engine with the AUII XR6 non VCT engine and also had the ECU reprogrammed with the AUII XR6 factory tune. The ute still has the original gearbox, torque converter and 3:24 diff but I believe the XR6 had a different torque converter and 3:45 diff. Will the XR6 tune cause any damage to the gearbox and diff the only difference is the ute has to be doing 102kmph and above for the converter to lockup. I checked the speed using GPS from 50,60,70,80,90 and 100kmph and it has been spot on. I have a second ECU that Matthew from BPR did a custom tune keeping the original gear shift schedule and copying over the XR6 engine tune over with a perf95 conversion which is awesome but the factory XR6 gear shift seems way better in take off and overtaking. I also use the ute to tow a 6 meter fibre glass boat so I don't know whether changing the diff and speedo cog is going to be any advantage unless I really have to. Thanks.

xr6 has 3.45 diff ratio, but torque converters are the same..

Thanks is there going to be any issues with the XR6 tune 3:45 diff ratio compared to the XL stock diff ratio 3:24. I'd like to go back to the factory XR6 ECU but just not to sure what problems I might get later on with the different diff ratios. By the way I've looked all over the diff but can't find a label or anything that I can identify what diff ratio it is just assuming its a 3:24.