2 types of Serpentine Belt on GMPartdirect?

[stillriza]

Hi

I am trying to price a serpentine belt from GM but I am given an option of purchasing 2 (what appears to be) diff. belts. It does not give me a part number for either. Can someone explain the diff b/w the two? My GA is from the 2003.5 model year but not sure if they would consider it just a regular 03 model.

From GMpartsdirect website...

Serpentine belt, 3.4l, grand am, w/6-rib cogged 01-04 $21.22
Found under Maintenance & lubrication >> Engine service >> Belts & pulleys >> Serpentine belt

And there is

serpentine belt - 3.4 liter - 3.4 liter 99-03 $21.22
Found under Cooling >> Belts and pulleys >> Serpentine belt

[black05GT]

I have found from experience with my '05 GAGT is that there are two lengths of serpentine belts for the 3400, depending on whether the car is before or after 2003 - my '05 took the longer belt - the part number is
12578869 . You can also replace the serp belt with a Good year Gatorback belt (again you might need the longer of the two available part numbers)
gmpartsdirect info :
GM PART # 12578869
CATEGORY: Belts, Engine Drive
PACK QTY: 1
CORE CHARGE: $0.00
GM LIST: $61.75
OUR PRICE: $32.10

[nickofcourse]

any reason why there would be a differance? what did they change. just curious :D

[stillriza]

I have found from experience with my '05 GAGT is that there are two lengths of serpentine belts for the 3400, depending on whether the car is before or after 2003 - my '05 took the longer belt - the part number is
12578869 . You can also replace the serp belt with a Good year Gatorback belt (again you might need the longer of the two available part numbers)
gmpartsdirect info :
GM PART # 12578869
CATEGORY: Belts, Engine Drive
PACK QTY: 1
CORE CHARGE: $0.00
GM LIST: $61.75
OUR PRICE: $32.10

Interesting. Mine is the 03.5... I think I will head to a dealer and have them tell me what part I need from giving them my vin.