AR handguard replacement question

[lear60man]

Below is a link to a pic of my gun. I want to replace the handguard in the pic with a quad rail. The current handguard is a touch over 12".

The barrel is 20", so what specific parts do I need to buy? I found out the hard way that not all pieces are swappable and require other pieces to make it work. I would like to buy 'the other pieces' all in one purchase and not get frustrated. Thanks.

http://www.model1sales.com/index.cfm?fuseaction=category.display&category_id=79

[biglou]

Depends which ones you get. An example like YHM below would come with all hardware included. I'm sure no matter who you buy from they will sell you the parts.

http://yankeehillmachine.com/store/product439.html

[ADH]

Most FF forearm kits (if not all) will come with the required barrel nut as many of them use proprietary parts anyway.