Chrysler 300 Alternator Replacement Guide (1973-1977)
Keep your classic 1973-1977 Chrysler 300 on the road by understanding its unique charging system and how to choose the right replacement alternator.
- Your 1973-1977 Chrysler 300 uses a 'square back' style alternator that was known for weak output at idle.
- You can choose between a direct-fit remanufactured part or a new, high-output aftermarket upgrade.
- If you upgrade to a high-output alternator, you must also upgrade the main charging wire to prevent a fire risk.
- No specific alternator recalls or TSBs were found for this model year range.
Understanding Your Chrysler 300's Alternator
The alternator on the 1973-1977 Chrysler 300 is a specific design known as a "square back" alternator, which Chrysler began using around 1972. These were externally regulated, meaning a separate part, the voltage regulator, controls the alternator's output. A known characteristic of this original charging system is that it can have weak output at low engine speeds, like at a stoplight. This can cause lights to dim at idle, a common experience for owners of Mopars from this era.
Symptoms of a Failing Alternator
When your alternator starts to fail, it gives several warning signs. Ignoring them can leave you stranded with a dead battery.
- Dimming or Flickering Lights: Headlights and dash lights may dim, especially at idle, and then brighten as you accelerate. This is a classic sign of a weak alternator struggling to meet the car's electrical demands.
- Weak or Dead Battery: The alternator's primary job is to recharge the battery. If you find yourself needing to jump-start your car frequently, the alternator is likely not doing its job, even if the battery is new.
- "ALT" or Battery Warning Light: Your dashboard may have a warning light (often shaped like a battery) that illuminates if the system voltage drops below a certain level, indicating a charging problem.
- Strange Noises: A grinding or whining sound from the front of the engine can point to bad bearings inside the alternator.
- Electrical Issues: The radio acting up, gauges behaving erratically, or other electrical gremlins can occur when the alternator can't provide stable power.
No Recalls or TSBs Found
Searches of the National Highway Traffic Safety Administration (NHTSA) database and other sources did not find any specific recalls or Technical Service Bulletins (TSBs) for alternator issues on the 1973-1977 Chrysler 300. Recalls found were for much newer models.
Choosing the Right Aftermarket Alternator
Original OEM new parts are no longer made. Your choices are remanufactured parts, which are rebuilt original units, or new aftermarket parts. There are two main paths: a direct-fit replacement or a high-output upgrade.
1. Stock Replacement (Remanufactured)
This is the simplest option. A remanufactured alternator from brands like Carquest, Duralast, or Bosch is designed to be a direct replacement for the original. These will have the stock amperage (often around 60 amps) and will work with your car's original external voltage regulator and wiring.
- Pros: Easy installation, lower cost, maintains original setup.
- Cons: Retains the original design's weakness of low output at idle.
2. High-Output Upgrade (New Aftermarket)
If you've added electrical accessories like a modern stereo, electric fans, or brighter headlights, a high-output alternator is a smart upgrade. Brands like Powermaster and Tuff Stuff offer new alternators that look like the original "square back" but produce much more power (95 amps or more). Many of these are "1-wire" alternators, which have an internal voltage regulator and simplify wiring.
- Pros: Significantly more power, especially at idle, which prevents dimming lights and supports modern accessories. A "1-wire" setup can clean up the engine bay.
- Cons: More expensive. May require wiring upgrades to be safe. Pro Tip: Upgrading to a high-amp alternator without also upgrading the main power wire from the alternator can create a fire hazard. The factory wiring was not designed for higher amperage.
| Part Type | Estimated Cost |
|---|---|
| New OEM (NOS) | Not generally available |
| Remanufactured (Stock Amperage) | $95 - $150 |
| New Aftermarket (High Output) | $200 - $400+ |
| Shop Labor | $100 - $200 |
Frequently Asked Questions (FAQ)
What is a "1-wire" alternator?
A "1-wire" alternator has an internal voltage regulator, simplifying installation. It only needs one heavy-gauge wire running from its output post to the battery. This is a popular modification for classic cars to get more power and a cleaner look under the hood compared to the original external regulator setup.
If I get a high-output alternator, do I need to change my wiring?
Yes, it is highly recommended. The original wiring in your Chrysler was designed for a lower-amperage alternator. Running a 100+ amp alternator through the original, smaller-gauge wires and factory ammeter can overload them, causing them to melt and potentially start a fire. At a minimum, you should run a new, thicker wire directly from the alternator's output post to the battery (or starter relay positive post) and bypass the factory ammeter gauge.
Can I replace the alternator myself?
Yes, for a mechanically experienced person, this is a very feasible DIY job. These cars have plenty of room in the engine bay. The process involves disconnecting the battery, loosening the belt tensioner to remove the drive belt, unbolting the old alternator, and then installing the new one in reverse order. The difficulty is low for a stock replacement but moderate if you are upgrading and need to modify wiring.
What amperage do I need?
For a stock vehicle with no major electrical upgrades, a standard 60-78 amp remanufactured unit is sufficient. If you have added or plan to add an electric cooling fan, a powerful sound system, or other modern electronics, an alternator with 100 amps or more is a good investment to ensure the system isn't strained.
Technical Specifications
OEM Part Numbers: 3438165 3438168 3438176 3438177 3438178 3438179 3438180 3438183 3438184 3438809
Vehicle uses a 'square back' style, externally regulated alternator. Stock amperage is typically 60-78 amps. Upgrades are available up to 200+ amps, often with internal regulators ('1-wire'). Pulley type is a V-belt, with single or double groove options available.
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.