Used Rear Axle Assembly Buyer’s Guide

A used rear axle assembly is one of the best value plays in the used auto parts market. New OEM rear axle assemblies for trucks run $900–$2,500 depending on make and whether you need limited slip. Used assemblies from low-mileage donors — with gear ratio confirmed and limited slip type matched — cost $320–$850. The assembly components that cause problems at high mileage are all serviceable items with significant remaining life on a properly sourced used unit.

The details matter here: gear ratio must match (critical on 4WD), limited slip type must match (open vs. LSD changes traction behavior), and the axle width must match your truck’s track width. Get all three right and a used rear axle assembly is one of the lowest-risk used part purchases you can make.

Top Makes — Rear Axle Assembly Sales at FirstChoice

Based on actual order data, rear axle assemblies average $565 per unit in gross profit — among the highest of any single-part category. The mix of makes reflects the truck-dominated buyer base:

Used Rear Axle Assembly Cost by Make

Make / Model	Axle Type	Used Price	New OEM Price	Savings
Ford F-150 (2004–2014)	Ford 8.8-inch	$350–$550	$950–$1,400	~60%
Ford F-150 (2015+)	Ford 9.75-inch	$450–$700	$1,200–$1,800	~60%
Ford F-250 / F-350	10.5-inch Sterling	$500–$800	$1,500–$2,300	~65%
Chevy/GMC Silverado Sierra 1500	GM 8.6-inch 10-bolt	$320–$520	$900–$1,300	~60%
Chevy/GMC Silverado Sierra 2500HD	GM 9.5-inch 14-bolt	$500–$800	$1,400–$2,100	~62%
Dodge RAM 1500 (2002+)	AAM 9.25-inch	$380–$600	$1,100–$1,600	~62%
Dodge RAM 2500 / 3500	AAM 11.5-inch	$550–$850	$1,600–$2,500	~65%
Jeep Grand Cherokee (V8)	AAM 9.25-inch	$380–$580	$1,100–$1,700	~62%
Toyota Tacoma 4WD (2005–2023)	Toyota 8.4-inch	$380–$600	$1,100–$1,700	~62%
Toyota Tundra	Toyota 9.5-inch	$450–$700	$1,300–$2,000	~62%

Cluster Guides

The 3 Non-Negotiable Compatibility Factors

1. Gear Ratio — Must Match on 4WD/AWD

The gear ratio (3.55, 3.73, 4.10, etc.) determines how many times the driveshaft rotates per single wheel rotation. On 4WD and AWD vehicles, front and rear ratios must be identical — even a small mismatch causes constant driveline binding that destroys the transfer case over months. On RWD vehicles, the ratio still affects performance and fuel economy and should match the original unless you’re deliberately regearing.

How to confirm your ratio:

• Axle tag: Metal plate on differential cover bolts — most reliable
• GM RPO sticker (glove box): GU4 = 3.42 | GU6 = 3.73 | GT4 = 3.08 | GT5 = 3.42 | GU2 = 4.10
• Ford door jamb sticker: Axle code listed in the certification label
• Chrysler SPID sticker: Axle ratio code in trunk or glove box

2. Open vs. Limited Slip — Must Match Your Original

Installing an open differential assembly in a vehicle originally equipped with limited slip removes the LSD traction benefit and changes how the vehicle behaves in low-traction situations. Installing a limited slip assembly in a vehicle originally equipped with open differential changes nothing negatively — you gain traction. But for warranty purposes and driver expectations, like-for-like matching is best practice.

3. Axle Width and Flange Pattern — Verify for Body-Lifted or Modified Trucks

For stock-height trucks, the axle from the same year/make/model will be the correct width. For lifted trucks, custom suspension, or older trucks with known running changes (Ford made mid-year axle flange changes on F-150 in 2011), confirm the axle width and lug pattern match your brake rotors and wheel hubs before ordering.

Used vs. Rebuilt Rear Axle Assembly

	Used OEM Assembly	Rebuilt / Remanufactured	New OEM
Cost	$320–$850	$700–$1,400	$900–$2,500
What you get	Original OEM assembly; mileage-dependent	Original housing with new ring/pinion, bearings, seals	Factory new
Warranty	30–90 days	1–3 years typically	2–5 years
Gear ratio set?	Yes — as pulled from donor vehicle	Yes — specified at order	Yes
Best for	Under 120K mile donor; budget repair	High-mileage vehicle or ring/pinion is the confirmed failure	Newer vehicles or high-use commercial applications

5-Step Ordering Process

1. Confirm your gear ratio. Use the axle tag, RPO sticker, door jamb code, or the manual count method (mark one wheel; count driveshaft turns per 4 wheel rotations). Do this before calling — it makes the conversation 10 minutes shorter.
2. Identify open vs. limited slip. Use the 30-second test above. Tell the supplier your result — they’ll match accordingly. If you’re upgrading from open to limited slip, tell them that too so they fill with the correct LSD friction modifier fluid.
3. Specify your vehicle’s cab style and trim. Affects brake backing plate configuration on some models (crew cab vs. regular cab may have different backing plate dimensions in certain years).
4. Request mileage documentation and gear ratio confirmation from the supplier. A supplier who can tell you the donor vehicle’s mileage and confirm the ratio from the axle tag is giving you verified information. “Should be 3.73” is not the same as “tag reads 3.73.”
5. Order the correct differential fluid alongside the assembly. Fill with the correct fluid before installation: 75W-90 for open differentials; 75W-90 + LSD additive (or 75W-140 full synthetic) for limited slip. Filling with the wrong fluid causes LSD chatter immediately.

Frequently Asked Questions