Firstly, you have posted in the Mk2/2b subforum, but your car is the later Grande, so the query would be best asked in the Grande subforum. Then you are more likely to get answers from fellow owners.
As you've replaced the gearbox from an '07 model, with one from a '14 model, there is a possibility that the speed sensor is different. That could present a real can of worms.
If the old and new sensor look similar, fitting the old one into the new box might work. If they look different, don't try it, as if they foul inside the box the debris may damage stuff.
It is possible that the speed signal given is different, and the car cannot read it properly, or that the wiring connectors are not in the same order in the newer sensor. It is doubtful you'll fix those issues.