interesting front rotor cross-index

[3.4 slow to go]

looking up rotors for a 2001 ellis juan car, and my 99 GP
(parts on advance auto web site)

ellis jaun p/n: YH145150
gp: YH145250

other cars for that can fit the ellis juan rotor:
Wearever BRAKE ROTOR WREVR
Part Number: YH145150
This product fits the following vehicles - click on a vehicle to see detailed engine information.
BUICK back to top
2000 - 2004 LESABRE

1997 - 1999 RIVIERA
1997 - 2005 PARK AVENUE
CADILLAC back to top
1997 - 1999 CONCOURS

1997 - 2002 ELDORADO
1997 - 2004 DEVILLE

1997 - 2004 SEVILLE
CHEVROLET back to top
1998 - 2002 CAMARO

2000 - 2004 MONTE CARLO
2000 - 2005 IMPALA
OLDSMOBILE back to top
1996 - 1999 AURORA

1998 - 1999 INTRIGUE
2001 - 2003 AURORA
PONTIAC back to top
2000 - 2003 BONNEVILLE

1998 - 2002 FIREBIRD

now for the gp:


Wearever BRAKE ROTOR WREVR
Part Number: YH145250
This product fits the following vehicles - click on a vehicle to see detailed engine information.
BUICK back to top
1997 - 2005 CENTURY

1997 - 2004 REGAL
1999 - 2005 LESABRE
CHEVROLET back to top
1997 - 2005 VENTURE
OLDSMOBILE back to top
1999 DELTA 88

1998 - 1999 LSS
1998 - 2002 INTRIGUE

1997 - 2004 SILHOUETTE
PONTIAC back to top
1998 - 2003 BONNEVILLE

1999 - 2005 MONTANA
2005 BONNEVILLE

1997 - 1998 TRANS SPORT
1997 - 2003 GRAND PRIX

I'm seeing the LeSabre, Intrigue, & Bonnie as compatable. I am wrong here? I wonder what the last 3 numbers of the p/n mean?????