Cokin Holder for GND and Polarizer

I need help choosing a Cokin holder that will allow for my Hoya circular polarizer (which does not allow other filters to be attached to it) and GND's for my Tamron 17-50 mm lens (67mm.

I am considering the Hitech 85/P ND filters (.6 and .9 )graduals with a Cokin P Wide Angle holder but the holder does not have a slot for a polarizer.

Any suggestions would be appreciated. Thanks! Michel

I'm using the Singh Ray LB warming polarizer, which will fit into the P type Cokin holder and can still be turned. It's called the Cokin P Sprocket Mount, and it fits into the first slot nearest the camera (thin slot). Here's a link: http://www.singh-ray.com/polarizers.html

Be careful, sometimes the sprocket mounted polarizer will vignette withsome wide angle zooms. It is probably OK with a 67mm threaded lens but it may have slight corner vignettes especailly at 17mm. If you can go to a local camera store try out a Cokin version of the sprocketed polarizer to see if it vignettes. Cokin's polarizers are not great, a little soft, so I would buy a singh-ray version if the sprocket polarizer does not vignette with your lens.

Many thanks for your comments and suggestions.I will check out these options.