Power Brake Boosters?
 

So I'm using the OEM vacuum actuated brake booster on my project car and wondering if anyone has ever welded to a booster before? Id like to use an AN weld on bung instead of the clamp on vacuum line. I have no idea whats inside one so before I throw some heat at something that has to stop the car id like to know a little big about how the function and whats found inside. Any one?