Thermal pad replacement comments?

I took my AirPort Extreme apart to give it a clean because it was full of dust. I thought I would remove the heat sinks just for interests sake. When I removed the heat sink I noticed it had a thermal pad between the sink and the Broadcom router chip. I was a little disappointed this was not mentioned in any of the tear downs as I like to replace thermal pads when I pull things apart. I had to put it back together as was but I am looking to replace the thermal pad. Does anyone have any suggestions? Also any suggestions on pad thickness? I was thinking 3mm from memory. IT seemed like a fairly big gap from memory. Any comments greatly appreciated. Also from memory there was definitely only one thermal pad yes?