If the reason for changing it is because it is interferring with the radio/tv then you might be best changing the boiler t/stat complete.The suppressor is usually found across the gasvalve connections,so swap like for like,but if the t/stat is arcing it might not make much difference just changing the suppressor.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix home heating systems.