When you create a restriction on the network and set up the vehicle height parameter for that restriction, the value you put in there is simply the default. You can adjust that value before solving your analysis.
The best thing to do is to create two travel modes, one for each truck. A travel mode includes all the analysis settings, such as restrictions and parameters, that will be applied for the analysis. In the Restrictions section of the travel mode configuration, set the vehicle height parameter value to the appropriate value. In other words, you can just override the default value of the parameter using the correct value for the truck you're trying to model.