Is there a modern equivalent for windscreen piece 6152?
The windscreen you mentioned has been retired, however you can still get it on BrickLink. It is available inexpensively in several colors: http://www.bricklink.com/catalogItem.asp?P=6152

If you want to use a modern version, this wedge is pretty close in shape and is available in current sets: http://www.bricklink.com/catalogItem.asp?P=6153b

As a reference, here are all the LEGO windscreens LEGO ever made. You can browse them by year released and sets they appear in: http://www.bricklink.com/catalogList.asp?catType=P&amp;catString=115

And here are all the wedge elements LEGO ever made. They tend to use these more often these days, most likely because of the stronger/thicker walls: http://www.bricklink.com/catalogList.asp?catType=P&amp;catString=42