Overnight bus: Bangkok to Khao Lak?

Hello all -- great forum!

Does anyone have information about overnight bus service from Bkk to Khao Lak?

I%26#39;d certainly prefer 1st class sleeper accommodations, but I%26#39;m flexible.

All of the bus service sites I%26#39;ve visited are in Thai only -- mai kao jai, khrap!

Thanks in advance...