There used to be a Urethane Groove (with a pancake core) around for years, AFAIK the only offering before the Avalanche. It came dull (400 grit matte, I think) and offered more hook than one would expect from such a piece.

 

Before that, there were e. g. the Phantoms (early 90ies, I guess), which coupled urethane with an asymmetrical core - but these are rather collector's items.

DizzyFugu - Reporting from Germany
2010/11 Benrather BC Club Champion
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To the best of my knowledge there was never an LT-48 that was made of urethane. There was a rubber ball that was called "Johnny Petraglia LT-48". In the mid to late 1990's  there were two reactive balls that had this name: the first was the "johnny Petraglia LT-48 Gold. This was a solid. There was also a "Johnny Petraglia LT-48 Gold Pearl.

 

Brunswick has been making urethane bowling balls since the early 1980's. Their current model is the Avalanche Pearl. Several years ago they made a solid urethane ball, the Groove. You may be able to find one if you're willing to look around a bit.

Thanks guys for your help.  I would be looking for 15 lbs  Thanks again.