Based on our experience swapping a grill between LP and NG, you might need a different regulator on the appliance as well.

Check ebay.

Looking at the Thermador Planning Guide, there is neither an LP nor a NG conversion kit for any of the Pro Grand ranges.

Pro Harmony Dual Fuel have an LP conversion kit, but the all-gas ones do not (nor is there a natural gas conversion kit.)

You will need to contact Thermador support to find out what nozzles and regulator will be needed. It's more than 6 easily-accessible nozzles, too, because you have to convert the oven burners as well in your all-gas range. Plus the griddle or grill, depending on what that additional location is.

Once you start getting into the regulator and manifold on a gas appliance, you would be wise to have a gas-certified technician do the work.

Would line to do this !!

Ah mine is 4 burnets grill and griddle probally differnt ah shucks !