Yukon Gear 4.88 Ring & Pinion Gear Set | Toyota 8" 4-Cylinder 4WD (1984-95 4Runner / 1979-95 Pickup)

Yukon Gear 4.88 Ring & Pinion Gear Set

For 1984–1995 Toyota 4Runner and 1979–1995 Toyota Pickup 4WD with Toyota 8" 4-Cylinder Differential

Overview

The Yukon Gear 4.88 Ring & Pinion Gear Set is a performance differential upgrade for Toyota trucks and 4Runners equipped with the standard 4-cylinder-style Toyota 8-inch dropout differential.

Featuring a 4.88:1 gear ratio and heavy-duty 29-spline pinion, this gear set provides deeper gearing than common factory ratios to restore mechanical advantage when running larger tires and improve low-speed performance for off-road, overland, and trail-oriented builds.

The 29-spline pinion is larger than the factory 27-spline configuration used in many original Toyota 4-cylinder third members. Vehicles retaining a factory 27-spline driveline flange require the matching 29-spline companion flange, pinion seal, and pinion nut for installation.

Key Features

• 4.88:1 differential gear ratio

• Designed for the standard Toyota 8-inch 4-cylinder-style differential

• Heavy-duty 29-spline pinion

• Larger pinion shaft than the original 27-spline configuration

• Precision-machined ring and pinion gears

• Heat-treated steel construction

• Designed for proper tooth contact and quiet operation when correctly installed

• Suitable for larger-tire, off-road, overland, and performance applications

• Available with or without the required 27-to-29-spline conversion hardware

• Yukon Y.E.S. Protection Plan eligible

29-Spline Pinion Upgrade

Many original Toyota 4-cylinder 8-inch differentials use a 27-spline pinion and companion flange. This Yukon gear set upgrades the differential to a larger 29-spline pinion.

Because the spline count changes, the original 27-spline driveline flange cannot be reused. Installation requires:

• 29-spline companion flange / yoke

• Matching 29-spline pinion seal

• Matching 29-spline pinion nut

Choose the conversion-hardware configuration if the differential currently retains its original 27-spline components.

Identifying the Correct Differential

This gear set is designed for the standard 4-cylinder-style Toyota 8-inch third member, commonly identified by three external reinforcement ribs.

The larger V6/Turbo-style Toyota 8-inch third member is commonly identified by four reinforcement ribs and a trapezoid-shaped upper rib and requires the corresponding V6/Turbo differential gear set.

• 3 ribs: Standard 4-cylinder-style Toyota 8" differential

• 4 ribs + upper trapezoid rib: V6/Turbo Toyota differential

Differential housing type determines gear-set compatibility. Verify the installed third member before ordering, especially on vehicles that may have received drivetrain or axle swaps.

Toyota 8" Differential Identification

Toyota used different 8-inch third-member designs across these vehicles, so identifying the installed differential before ordering is important.

Standard 4-Cylinder Toyota 8" Differential

• Commonly found in 20R, 22R, and 22RE applications
• Typically identified by three external reinforcement ribs
• Uses this 4-cylinder-style ring and pinion gear set

V6 / Turbo Toyota 8" Differential

• Typically identified by four reinforcement ribs and a trapezoid-shaped upper rib
• Commonly associated with 22R-TE and 3VZ-E applications
• Uses the separate V6/Turbo-style gear set

Because Toyota 8-inch third members are frequently swapped between vehicles, verify the actual differential installed rather than relying solely on engine type.

Vehicle Fitment

4WD models with the Toyota 8-inch 4-cylinder differential only.

Toyota 4Runner

• 1984–1985 Toyota 4Runner – 1st Gen – Toyota 8" 4-Cylinder Differential – Front & Rear
• 1986–1989 Toyota 4Runner – 1st Gen – Toyota 8" 4-Cylinder Differential – Rear Only
• 1990–1995 Toyota 4Runner – 2nd Gen – Toyota 8" 4-Cylinder Differential – Rear Only

Toyota Pickup

• 1979–1983 Toyota Pickup – 1st Gen – Toyota 8" 4-Cylinder Differential – Front & Rear
• 1984–1985 Toyota Pickup – 2nd Gen – Toyota 8" 4-Cylinder Differential – Front & Rear
• 1986–1988 Toyota Pickup – 2nd Gen – Toyota 8" 4-Cylinder Differential – Rear Only
• 1989–1995 Toyota Pickup – 3rd Gen – Toyota 8" 4-Cylinder Differential – Rear Only

Fitment Notes

• Designed for the standard 4-cylinder-style Toyota 8-inch differential

• 4.88:1 gear ratio

• Uses a 29-spline pinion

• Factory 27-spline applications require a matching 29-spline flange, seal, and pinion nut

• Does not fit the Toyota 7.5-inch IFS front differential used beginning in 1986

• Does not fit the V6/Turbo-style Toyota 8-inch third member

• Does not fit the special factory Toyota 4.88 third-member configuration with the offset pinion and thin ring gear

• Verify the installed differential rather than relying solely on the vehicle's original engine

• Front and rear gear ratios must match on 4WD vehicles

• Professional differential setup is required

• Proper gear break-in is required after installation

Product Specifications

Brand: Yukon Gear & Axle
Product Type: Ring & Pinion Gear Set
Differential: Toyota 8" 4-Cylinder Style
Gear Ratio: 4.88:1
Ring Gear Diameter: 8 Inches
Pinion Spline Count: 29
Construction: Heat-Treated Steel
Drivetrain: 4WD
Installation: Professional Differential Setup Required

Choosing 4.56 vs. 4.88 vs. 5.29 Gears

Gear-ratio selection should account for tire diameter, tire and wheel weight, transmission, permanent vehicle weight, highway use, terrain, and future tire plans. Larger or heavier tires reduce effective gearing, while bumpers, winches, sliders, skid plates, recovery gear, spare-tire carriers, roof racks, tools, and camping equipment increase the load the drivetrain must move.

The ranges below are Preserve Rad selection guidance for 4-cylinder Toyota 4WD builds rather than hard fitment limits. Two vehicles with the same tire diameter can benefit from different gearing when their transmissions, wheel/tire weights, permanent equipment, terrain, or highway usage differ.

Gear Ratio Selection Guide

Tire Size & Vehicle Weight Guide

Tire weight matters, not just diameter. A heavy mud-terrain tire on a steel wheel places more demand on the drivetrain than a lighter tire and wheel combination of the same diameter because the drivetrain must accelerate additional rotating mass.

Permanent vehicle weight can justify deeper gearing. Steel bumpers, winches, armor, sliders, skid plates, spare-tire carriers, tools, recovery equipment, camping gear, and other permanently carried equipment increase the load the engine must move. The weight ranges above are general selection guidance rather than fixed cutoffs.

Transmission and highway use matter. Automatic-transmission trucks and vehicles that spend substantial time climbing grades or carrying weight may favor deeper gearing sooner, while a lighter manual-transmission truck that spends most of its time at highway speed may favor the less aggressive ratio when tire size allows.

Future tire size matters. If a truck is currently on 33-inch tires but is being built around a planned move to 35-inch tires, choosing 5.29 gears can make more sense than gearing only for the current tire size and paying for another differential setup later.

Available Configurations

29-Spline Gears Only (Requires Conversion Hardware)

• (1) Yukon 4.88 Ring Gear

• (1) Yukon 4.88 29-Spline Pinion Gear

• Installation Instructions

• Requires the correct 29-spline companion flange, pinion seal, and pinion nut

29-Spline Gears + 27-to-29 Spline Conversion Hardware Kit

• (1) Yukon 4.88 Ring Gear

• (1) Yukon 4.88 29-Spline Pinion Gear

• (1) 29-Spline Companion Flange / Yoke

• (1) Matching Pinion Seal

• (1) Matching Pinion Nut

• Installation Instructions

The conversion-hardware configuration provides the components required when converting an original 27-spline Toyota differential to the 29-spline Yukon pinion setup.