Outer barrel / Suppressor help

[ap27]

I'm looking to replace the bull-type barrel on my SL8 with a threaded outer barrel so I can add a suppressor onto the end of the rifle.

This is what the bull barrel looks like at the moment. Since the actual threaded end is currently inside the handguard, I need an outer barrel extension of sorts just to get the threaded end outside of the handguard so I can attach a suppressor. The suppressor will be long enough to cover the protruding inner barrel, naturally.

In the picture, the outer barrel is placed at the approximate length where it would meet the threads inside the handguard, just to give an idea of the length of extension required.

Can anyone tell me what type of outer barrel/extension/part I should be looking for? Would it be an outer barrel of a G36? Should it be C/K/E length?

[ap27]

Anyone? Pretty please??