Robertshaw makes most of the thermostats for N. American gas ranges.
Are you sure it's the thermostat that's hooped?
There is another device on older models with pilot lights called a thermo-coupler. This has a bulb that sticks into the pilot light. When it senses no heat, it shuts off the gas to the whole system.
Call a plumber of gas fitter to install the thing. Service guys are made to sell factory parts,and the factory parts are Robertshaw.