Just wondering if there's enough tollerence in the 15" box designs to fit a 17" lcd, such as the Samsung 740b 17" lcd.?????

Also, does anyone know where to get a below and adjustment mechenism - as seen in old photo enlargement equipment, etc. I thought that would be a cool way to mount the Pro lens on a 15" box rather than having to use a big wood sled.

I would say no. The 15" box is designed to fit a 15" LCD. If there was tolerance built in, than you would have light leakage. With that said, the boxes built here are not necessarily standardized. You build what works for you in as space saving a manner as you can, but still allowing for all of your components to fit. If you are planning on buying a 15" pre-made box, then a 17" LCD would certainly not fit into this.