Accessory drives have always...
Accessory drives have always been a hassle when it comes to engine swapping, but armed with this information, your choices become much easier and less expensive.
One of the hottest engine swaps in our world right now is the Gen III/IV (or LS, if you prefer) engine transplanted into a '60s or '70s GM muscle car. These engines not only are more powerful than the old Gen I small-blocks, but they're also lighter, don't leak, are easier to work on, and are far more efficient. It's everything a car crafter could want, but swappers have discovered that these engines don't bolt in to a Camaro, Chevelle, or Nova without modifications. While there are quick and expensive ways to mount an alternator, power steering pump, and air conditioning compressor, our goal is to show you how to do this while watching that budget. The good news is that you can get what you need without having to spend big dollars. It all depends on how trick you want to get.
GM Accessory-Drive Layouts
All factory GM systems place the alternator and power steering pump on the driver side with the A/C compressor mounted low on the passenger side driven by a separate belt. Within this basic layout, there are three significant variations based on whether the system was designed for a truck, the original LS1 Camaro/Firebird platform, or a Corvette. As for the A/C, all three systems mount the A/C pump in generally the same spot, but the mounts are not interchangeable.
This is the stock configuration...
This is the stock configuration for the Camaro/Firebird accessory drive found on '98 to '02 F-cars minus the A/C pump. The easiest way to spot this design is by the power steering pump on top on the driver side with the alternator below. This is also the drive arrangement for the GMPP kit PN 19155066.
The Corvette drive is the tightest to the front of the engine and places the alternator on top with the power steering pump underneath. This arrangement is wider at the top, offering maximum clearance toward the bottom of the engine. The next system was used on the Camaro/Firebird and early CTS-V Cadillacs that employ a harmonic balancer that projects out farther than the Corvette. This drive system places the power steering pump on top on the driver side with the alternator positioned underneath. The third orientation is the truck/SUV that uses the deepest balancer, pushing the accessory drive the farthest forward on the engine. The truck orientation is the narrowest and tallest of the three drives with the alternator up top and the power steering pump underneath. The truck system is the most common of the three but is the least visually attractive. It may also present hood clearance problems on cars with low hood lines. It cannot be used with any passenger-car LS EFI intake manifold because of interference between the throttle body and the idler pulley.
We also discovered a glitch where an F-car-style factory alternator bracket bolts to an aluminum 5.3L block (and we'll assume most other aluminum blocks), but when we tried to bolt it to an iron 6.0L block, there was one missing bolt location on the block and another that was not drilled or tapped. It's unclear whether this missing bolthole extends to all iron blocks. Roger Kunkel sent us a photo of his solution based on an F-car alternator rear mount location, leaving the missing bolt out of the front mount.
While we have not performed this swap, it does appear that a Gen III LS1 F-car accessory drive, for example, will bolt on to the later LS2 or LS3 engines (Gen IV) as long as the F-car balancer is used. Also keep in mind that if you change balancers, you must follow the factory-recommended procedure for torquing the factory balancer bolt. The spec requires an initial torque of 37 ft-lb and then using the torque angle method to tighten the bolt an additional 140 degrees. This technique applies to the one-time-use torque-to-yield GM bolt. If you plan on lots of swaps, consider going to a reusable ARP bolt.
 The typical Corvette LS1/LS6...  The typical Corvette LS1/LS6 accessory drive layout places the alternator on the top of the driver side with the power steering pump located below. This is also the orientation for the GMPP kit PN 19155067. |  This is the truck accessory...  This is the truck accessory drive arrangement that is very tall. We measured this setup on our '66 Chevelle, and the alternator will just barely clear the hood. If you're looking for the least expensive system that will bolt in place in a tall engine compartment (like a '55 Chevy), this is a good choice. If the engine is fuel injected, this drive system requires using a truck intake manifold, since the car throttle body won't clear that top idler pulley. |  This is a factory F-car alternator...  This is a factory F-car alternator mount bolted to an iron 6.0L block using a rear support bracket. Roger Kunkel used this factory accessory drive in his '71 Nova. |