what do I need to tap into TT propane for grill?

What I had on my old trailer was a Marshall Extend-A-Flow kit with hose. It allows you to "tee" off your tanks. Simple install and works great:

Extend-A-Flow

Something like this should work for you. It's pretty darn easy, and I've had success with it.

http://www.campingworld.com/shopping/item/stay-a-while/30339

Hi,

I have a propane tank tap on my motorhome, for it's 18 gallon tank. I never use it anymore though.

I find that a portable 1 gallon propane tank is really handy. Sure they are almost as expensive as the 5 gallon tanks from Costco, but the 1 gallon tank is smaller, and easy to move about. It will run my grill all summer, and only cost about $2 to refill. Much less expensive then replacing the disposable tanks. At $3 each for 1 pound, that is about $13 per gallon!

The motorhome tank is under my awning, and sometimes I want to grill someplace other than near the passenger door. Also if the wind is blowing, I like to set up the grill near the back or downwind side of the RV, so the portable tank does all this. I can also take the grill next door, while camping with friends.

Camping World does sell a extend a stay series of taps for the RV tanks. THey install between the high pressure propane line and the factory installed pressure regulator. It only takes about 5 minutes to install it yourself.

Have fun camping!

Fred.