Get on the urethane bandwagon with one of the balls that started it all!  My urethane Hammers hit harder than anything else I own.

This Black Hammer is a single drill. It was manufactured in Utah in 1993. I don't know the span or the exact weight as I bought it as part of a package from another bowler. If it was 15 I'd keep it for myself.

Cover's in great shape for a 17-year old ball.  No gouges or chips on this baby. Ball was just resurfaced to 320 grit sandpaper.

Pics here:

http://i554.photobucket.com/albums/jj420/dougb510/Balls%20for%20sale/SDC12185-1.jpg
http://i554.photobucket.com/albums/jj420/dougb510/Balls%20for%20sale/SDC12186.jpg

$60 shipped