What is the difference in these 3 part numbers?

12555220

12578068

12578067

 

I'm not sure about the differences in those part numbers, to my knowledge in 03 they updated the bracket to make it stronger and I thought all from 97-02 were the same... either of the brackets will work on any c5... usually the only people that need to get the stronger bracket have centrifugal superchargers that put a lot more tension and stress on the belt, the weaker brackets are known to break in those cases

 

I have never heard of failures and I have not experience
a failure on a SC. But I guess anything can break.

 

I have seen it on centrifugal blower cars, other than that they don't really break and I really have no idea why gm felt the need to change it but they did

 

Looks to be ls1 vs ls2, alternator part number is different.

19155066 NEW
Serpentine Accessory Drive System, with Air Conditioning

• Fits LS1 and LS6 engines
• Deluxe kit includes all the components and hardware necessary
to install on an engine with air conditioning, including alternator,
power steering pump and idler bracket, (belt included)
The system includes:
12572188 Belt (water pump, alternator, and power steering)
12569528 Belt (A/C compressor)
12568181 Tensioner Assembly
12560345 A/C Belt Tensioner Assembly
12557334 A/C Compressor Idler Pulley
1137031 A/C Compressor
12556444 A/C Compressor Bracket
15261472 Power Steering Pump (reman)
12555222 Power Steering Bracket
12578068 Alternator and Power Steering Pump Bracket
12555693 Power Steering Pump Brace
12559890 Power Steering Pump Pulley
10353440 Alternator
26046502 Power Steering Reservoir

19155067 NEW
Serpentine Accessory Drive System, with Air Conditioning
• Fits LS2 and LS7 engines
• Deluxe kit included all the components and hardware necessary
to install on an engine with air conditioning, including alternator,
power steering pump and idler bracket, (belt included)
The system includes:
12579229 Belt (water pump, alternator, and power steering)
12585476 Belt (A/C compressor, LS7)
12569301 Tensioner Assembly
12595289 A/C Belt Tensioner Assembly
12568996 Idler Pulley
88958093 A/C Compressor
12569286 A/C Compressor Bracket
15261472 Power Steering Pump (reman)
26046502 Power Steering Reservoir
12578067 Alternator and Power Steering Pump Bracket
12555693 Power Steering Pump Brace
12568997 Power Steering Pump Pulley
15841234 Alternator
12579228 Belt (A/C compressor, LS2)

 

I believe they stopped producing the earlier, lighter unit.

When I installed my blower, I went with a the new C5 version which has a visibly more stout design I think where the idler pulley is. It is now a solid section where before it had been more of a frame. I also added the steel LS2 power steering pulley.

I only think these are necessary if you have a centri blower and are strapping the belt down tightly or revving to the moon.

I found removing / installing that bracket the most frustrating thing on my car, but after the second time it is much easier.

 

More info.

OEM C5 accessory drive.

Alternator (1)10246634 (production) 10316182 (service)
Alternator to bracket bolts (2) 24503609
Alt bracket to head bolts (3) 11516357
Alt bracket to head bolt (1) 11516356
P/S fluid reservoir bracket (1) 12555222
P/S fluid reservoir (1) 26046502
P/S reservoir hose (1) 26046910
P/S reservoir cap (1) 26022453
P/S pump (1) 26046503
P/S pump pulley (1) 12559890
P/S pump brace (1) 12555693 Same as f-body
P/S pump bolts (2) 14078896 Same as f-body
P/S pump bolts (2) 11515758 Same as f-body
Belt idler pulley (1) 12564401 Same as f-body
Harmonic balancer (1) 12560115
Belt tensioner assembly (1) 12559325
A/C belt tensioner assembly (1) 12560345 Same as f-body
A/C belt idler pulley (1) 12557334
A/C compressor bracket (1) 12556444
A/C compressor (1) 1137031
A/C bracket stud (1) 12556447
A/C bracket bolt (1) 11515768
A/C compressor bolt (1) 11516714
A/C compressor bolt (1) 12552922
A/C compressor bolt (1) 11509202
A/C compressor nut (1) 10255857

 

If this is the stock Harmonic balancer (1) 12560115. I would pass on it because it will fail again

 

Little more info.

• GM Part # 12628771 - GM LS1 F-Body oil pan, gasket, stock baffle, drain plug and mounting hardware (Old GM Part # 12558899)
• GM Part # 12551581 - GM LS1 F-Body oil dip stick
• GM Part # 12551577 - GM LS1 F-Body oil dip stick tube
• GM Part # 12558251 - GM LS1 F-Body oil pickup tube
• GM Part # 12558253 - GM LS1 F-Body windage tray

Applications

• 1998-2002 Pontiac Firebird Formula and Trans Am
• 1998-2002 Chevrolet Camaro Z28 and SS
• Bolts to all GM Gen III & IV LS family engines including LS1, LS6, LS2, LS3, LS7, LS9, L76, L98, L92, L93, L99, LQ4, LQ9, LSA, LSX and V8 Vortec variations