Developed by Unrivaled Engineering, this serpentine kit provides a strong, reliable, and aesthetically refined accessory drive solution for Holden 304 and 308 engines. At the heart of the system is our extra-thick billet alternator bracket, CNC machined from 6061 aluminium and supplied with stainless steel hardware for long-term durability and corrosion resistance.
Engineered with strength, functionality, and aesthetics in mind, this system is designed to work seamlessly with our Unrivaled Engineering Eccentric Idler Pulley, creating an exceptionally rigid alternator mounting solution for Holden engines retaining the factory alternator location.
Unlike conventional alternator brackets, our kits are supplied with matching pulleys and a correctly sized belt to suit the combination. This allows us to reduce the length of the adjustment arm and position the alternator and bracket assembly as close to the engine as possible, improving packaging and reducing fitment issues commonly encountered in tighter Holden engine bays.
The alternator bracket is designed to suit Chevrolet-style alternators with 168mm mounting centres, providing access to a wide range of readily available charging options, including high-output units for EFI systems, electric fans, fuel pumps, and other modern electrical demands. We utilise the Chevrolet alternator platform due to its excellent aftermarket support and broad availability across performance applications.
Installation Note: Due to variations in water pump pilot diameters between manufacturers, please check the fit of the pulley centre pilot before installation. A small amount of hand filing may be required to achieve the correct fit.
Features
CNC machined from high-grade 6061 billet aluminium
Compact low mount driver's side configuration
Designed to position the alternator extremely close to the engine
Supplied with stainless steel mounting hardware
Compatible with Chevrolet-style alternators (168mm mounting centres)
Suitable for standard and high-output alternator applications
Why We Use an Eccentric Idler Pulley
Engineered to work with our Unrivaled Engineering Eccentric Idler Pulley system, this design delivers more than just belt adjustment. The eccentric idler introduces a controlled interruption point in the belt path, helping to dampen belt harmonics and reduce belt slap during engine operation. These belt oscillations occur in all belt-driven systems and are commonly encountered at specific RPM ranges, often contributing to premature belt wear, belt loss, and accessory drive instability. By
controlling belt movement and maintaining consistent tension, the eccentric idler improves belt life, reliability, and overall accessory drive performance.
Benefits
Increased bracket strength compared to traditional fabricated or cast designs
Reduced alternator movement under high RPM and belt loads
Improved belt control and reliability
Reduced belt harmonics and belt slap
Reduced risk of belt loss and premature belt wear
Compact installation for improved chassis clearance
Access to a wider range of high-output alternator options
Engineered as a complete serpentine drive solution, delivering improved reliability, superior belt control, and a clean, purposeful engine bay appearance
Fitment
Holden 304 V8
Holden 308 V8
Standard alternator mounting location
Chevrolet-style alternators with 168mm mounting hole centres
Specifications
Material: 6061 Billet Aluminium
Hardware: Stainless Steel
Alternator Type: Chevrolet Pattern
Alternator Mount Centres: 168mm
Belt Type: 6PK Serpentine
Mounting Position: Factory Holden Location
Variant Options
Finish:
Raw Billet Aluminium
Satin Black Anodised
Water Pump Configuration:
Long Water Pump
Short Water Pump
What's Included
Billet alternator bracket assembly
Unrivaled Engineering eccentric idler pulley
Matching 6PK serpentine pulleys
Correct-length 6PK serpentine drive belt
Stainless steel mounting hardware
Recommended Pairing
These components have been designed as a complete system to ensure correct alignment, maximum reliability, and trouble-free installation.
Ordering Notes
Please select both your finish option and water pump configuration when ordering.
All Unrivaled billet parts are considered aftermarket and suitable for racing/off road purpose, these are not OEM replacements fitment & vehicle safety is responsibility of vehicle owner. Unrivaled ensure that these parts are to the highest standards and fit the specified engines correctly. Vehicle fitment is responsibility of vehicle owner and pre purchase checking is advised before purchase of any billet aftermarket parts. There is no return on billet parts for change of mind or vehicle fitment issues.
