---
product_id: 8128314
title: "USA Standard Gear (ZG GM8.5-342) Ring & Pinion Gear Set for GM 8.5 Differential"
brand: "usa standard gear"
price: "A$604"
currency: AUD
in_stock: true
reviews_count: 13
category: "Usa Standard Gear"
url: https://www.desertcart.com.au/products/8128314-usa-standard-gear-zg-gm8-5-342-ring-and-pinion
store_origin: AU
region: Australia
---

# 3.42 axle ratio fit Precision-machined gears 1-year warranty coverage USA Standard Gear (ZG GM8.5-342) Ring & Pinion Gear Set for GM 8.5 Differential

**Brand:** usa standard gear
**Price:** A$604
**Availability:** ✅ In Stock

## Summary

> ⚙️ Upgrade your ride with precision and confidence — don’t get left behind!

## Quick Answers

- **What is this?** USA Standard Gear (ZG GM8.5-342) Ring & Pinion Gear Set for GM 8.5 Differential by usa standard gear
- **How much does it cost?** A$604 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.com.au](https://www.desertcart.com.au/products/8128314-usa-standard-gear-zg-gm8-5-342-ring-and-pinion)

## Best For

- usa standard gear enthusiasts

## Why This Product

- Trusted usa standard gear brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Risk-Free Upgrade:** Backed by a 1-year warranty, so you install with confidence and zero second-guessing.
- • **Perfect Fit for GM 8.5:** Vehicle-specific 3.42 ratio ensures seamless installation and optimal drivetrain harmony.
- • **Durability You Can Trust:** Rigorous in-house testing guarantees long-lasting strength and reliability.
- • **Wide Compatibility Range:** Supports models from 1948 to present, covering rare and common applications alike.
- • **OEM-Level Quiet Performance:** Engineered to exceed OEM specs for smooth, whisper-quiet operation.

## Overview

The USA Standard Gear ZG GM8.5-342 Ring & Pinion Gear Set delivers a precision-engineered 3.42 axle ratio solution tailored for GM 8.5 differentials. Designed to exceed OEM standards, it offers quiet operation, durable construction, and a perfect vehicle-specific fit. With rigorous quality testing and a 1-year warranty, this gear set is the trusted choice for both classic and modern GM builds seeking reliable drivetrain performance.

## Description

USA Standard ring & pinion sets are designed to provide a quality and quiet gear set for OEM replacement. USA Standard uses rigorous in-house quality testing and inspections to ensure products pass dimensional, material and fitment testing. USA Standard gears come in OE and aftermarket ratios, providing a wide variety of product to meet the needs of most any installation: from 1948 to present popular vehicle models. USA Standard gears are designed to exceed OEM specification while providing an affordable drivetrain solution. All USA Standard Ring and Pinion Gear Sets come with a standard one year warranty against manufacturing defects.

Review: Good quality. - Good quality. Installed and currently finished break in. Running quiet. Good so far.
Review: Notice for GM 12 bolt C10 diff install - These gears appear to be good quality and the wear pattern looks the best I've ever seen after adjustment. I have a 12 bolt 8.875 GM truck rear in my '67 C10. All 3 of my C10's, '67, '68, '69 2wd trucks had 3.08 factory installed gears. I guess because of only a 3 speed auto trans in my '67 and '68, it was better on the highway. My '69 is a 3 speed manual. I decided that since I built a 383 stroker small block and installed a 3000 rpm stall converter in the TH400, due to the cam profile, I would replace the 3.08 geared, one wheel peel with a 3.73 gear and a Spartan "lunch box" locker. I'm just about to fire this thing up in a week or two. Just waiting on the machine shop to do the final piston fit honing and it ready to assemble, stab it in, hook everything up, start it up, and hold onto my hat. But I digress. Sorry, lost track. Anyhow, changing the gears from 3.08 to 3.73 I obviously had to re-shim my carrier to move it to the left. The factory shims were just about equal from one side to the other. Left being a .230 and right being a .243 thickness. I had to bring my left side to .445 and the right only has .024 gap in order to get my .006-.010 backlash needed for a good pattern. I even had to shim my pinion an additional .030 just to get it right. It's not quite a tight fit as factory, but I don't have a housing spreader and the 3 very thin .008 shims were giving a fit without trying to fold over on me. I don't think .004" is going to give me any trouble. Especially with the Moser girdled diff cover I'm using. Okay, here's the issue I ran into. Being that I needed to shift the carrier over almost a quarter inch, the right side of the carrier was hitting the area just outside and to the front of the bore for the carrier bearing. So, I removed the carrier and used a dremel tool to slightly grind the carrier housing on the four 'corners' where the bearing is pressed on. I took off about .100" on each edge and it then fit like a glove. I got my backlash to .008". Installed the yoke with a new crush sleeve and torqued the pinion nut to 11 in.lbs. Re-installed my carrier and torqued the caps to 60 ft.lbs. and installed the diff girdle cover. Hint to the next guy that decides to rebuild a differential. Purchase some cheap new pinion bearings in addition to the bearings that you are going to install. Grind the inner race of the cheap bearings so they slide over the pinion without being pressed on. This will save a bunch of time and frustration when adjusting or shimming the pinion depth. When it's all clocked in, just remove the dummy bearings and press the final good bearings onto the pinion. Oh, btw, the spartan locker is a pain in the butt to install with the diff housing in the vehicle. If possible, remove it and set it on a bench or jack stands with the yoke facing the floor. It's much easier to articulate the c-clips this way as long as you hold your tongue right. Good luck

## Features

- USA Standard ring and pinion sets are the right choice to add confidence to your install
- USA Standard Gear offers a full line of ring and pinion sets for a variety of common and hard to find applications
- USA standard gear offers a standard one year warranty against defects on their ring and pinion sets
- This product is used in a 3.42 axle ratio
- Fit type: Vehicle Specific

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B0078UAGVS |
| Best Sellers Rank | #54,440 in Automotive ( See Top 100 in Automotive ) #2 in Automotive Replacement Differential Rings & Pinions |
| Brand | USA Standard Gear |
| Customer Reviews | 4.4 4.4 out of 5 stars (1,083) |
| Date First Available | February 13, 2012 |
| Exterior | Machined |
| Item Weight | 17.52 pounds |
| Item model number | ZG GM8.5-342 |
| Manufacturer | USA Standard Gear |
| Manufacturer Part Number | ZG GM8.5-342 |
| Model | Ring & Pinion Gear Set for GM 8.5 Differential 3.42 Ratio |
| OEM Part Number | ZG GM8.5-342 |
| Product Dimensions | 16 x 12 x 6 inches |
| Special Features | All USA Standard Ring and Pinion Gear Sets come with a standard one year warranty against manufacturing defects. |

## Images

![USA Standard Gear (ZG GM8.5-342) Ring & Pinion Gear Set for GM 8.5 Differential - Image 1](https://m.media-amazon.com/images/I/61AoTpgyw3L.jpg)

## Available Options

This product comes in different **Style** options.

## Customer Reviews

### ⭐⭐⭐⭐⭐ Good quality.
*by D***H on December 26, 2025*

Good quality. Installed and currently finished break in. Running quiet. Good so far.

### ⭐⭐⭐⭐⭐ Notice for GM 12 bolt C10 diff install
*by R***T on August 3, 2019*

These gears appear to be good quality and the wear pattern looks the best I've ever seen after adjustment. I have a 12 bolt 8.875 GM truck rear in my '67 C10. All 3 of my C10's, '67, '68, '69 2wd trucks had 3.08 factory installed gears. I guess because of only a 3 speed auto trans in my '67 and '68, it was better on the highway. My '69 is a 3 speed manual. I decided that since I built a 383 stroker small block and installed a 3000 rpm stall converter in the TH400, due to the cam profile, I would replace the 3.08 geared, one wheel peel with a 3.73 gear and a Spartan "lunch box" locker. I'm just about to fire this thing up in a week or two. Just waiting on the machine shop to do the final piston fit honing and it ready to assemble, stab it in, hook everything up, start it up, and hold onto my hat. But I digress. Sorry, lost track. Anyhow, changing the gears from 3.08 to 3.73 I obviously had to re-shim my carrier to move it to the left. The factory shims were just about equal from one side to the other. Left being a .230 and right being a .243 thickness. I had to bring my left side to .445 and the right only has .024 gap in order to get my .006-.010 backlash needed for a good pattern. I even had to shim my pinion an additional .030 just to get it right. It's not quite a tight fit as factory, but I don't have a housing spreader and the 3 very thin .008 shims were giving a fit without trying to fold over on me. I don't think .004" is going to give me any trouble. Especially with the Moser girdled diff cover I'm using. Okay, here's the issue I ran into. Being that I needed to shift the carrier over almost a quarter inch, the right side of the carrier was hitting the area just outside and to the front of the bore for the carrier bearing. So, I removed the carrier and used a dremel tool to slightly grind the carrier housing on the four 'corners' where the bearing is pressed on. I took off about .100" on each edge and it then fit like a glove. I got my backlash to .008". Installed the yoke with a new crush sleeve and torqued the pinion nut to 11 in.lbs. Re-installed my carrier and torqued the caps to 60 ft.lbs. and installed the diff girdle cover. Hint to the next guy that decides to rebuild a differential. Purchase some cheap new pinion bearings in addition to the bearings that you are going to install. Grind the inner race of the cheap bearings so they slide over the pinion without being pressed on. This will save a bunch of time and frustration when adjusting or shimming the pinion depth. When it's all clocked in, just remove the dummy bearings and press the final good bearings onto the pinion. Oh, btw, the spartan locker is a pain in the butt to install with the diff housing in the vehicle. If possible, remove it and set it on a bench or jack stands with the yoke facing the floor. It's much easier to articulate the c-clips this way as long as you hold your tongue right. Good luck

### ⭐⭐⭐⭐⭐ Just get it
*by J***T on November 6, 2025*

Installed these into my 87 square body and had no issues! Was able to get the pattern on the first try and have had no issues with the rear end since the rebuild!

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*Product available on Desertcart Australia*
*Store origin: AU*
*Last updated: 2026-03-09*