Here's the breakdown for cranksets for Pistas over the years:
2005 - Sugino RD (170 actual length, 165mm pedal hole)
2004 - Truvativ
2003 - Truvativ
2002 - Bianchi Cyclone
2001 - Bianchi Cyclone
I wouldn't worry about it if you have a year prior to 05 - in fact, I wouldn't even worry about the 05's. Makes no difference aside from aesthetics.